Basic Installer Study Guide
The Basic Installer Study Guide is based on carefully documented material and research. Every attempt has been made
to relay accurate and up-to-date information. This book is
designed to assist Mobile Electronics Installers in passing the
MECP Basic Installer Test and can also be used as a reference
guide. MECP and/or the Consumer Electronics Association
cannot be held responsible for discrepancies or inconsistencies contained in this publication.
Copyright © 2000 by Consumer Electronics Association/
First Edition
All rights reserved. No part of this work covered by the
copyright hereon may be reproduced or used in any form or
by any means - graphic, electronics, or mechanical, including photocopying, recording, taping or information storage
and retrieval systems - without the written permission of the
publisher.
MECP
Consumer Electronics Association
2500 Wilson Boulevard
Arlington, Virginia 22201-3834
(703) 907-7689
CONTRIBUTORS
WRITERS AND CONTRIBUTING EDITORS
Eric Abbiss
Wayde Alfarone
Paul Baird
John Banse
Ward Benjamin
Bob Bentley
Jim Boyte
Kris Bulla
Dennis Deck
Tim Den Hartog
Charlie Fox
Mark Fukuda
Joe Garruba
Tom Gazda
Doug Giddens
Mary Ann Giorgio
Lonnie Goddard
Mark Gordon
Jeff Halkin
Homer Hawlins
Scott Heidbrink
Stan Hoffman
Jim Jardin
Dan Jobin
Ed Kuehner
Derek Lee
David Long
Martin Marino
James Milton
Ted Peterson
Joe Petreau
Todd Ramsey
Rudy Sanders
Allen Schultz
Kerry Shrode
Geoff Smith
Kenny Snoddy
Dave Sprosty
Justin Stanley
Jerry Sterling
Gil Stroud
Todd VanZandt
Joe Walters
Paul Wanders
Ken Ward
MECP would like to
thank the following
manufacturers:
Alpine, Code Alarm,
Directed Electronics,
Kenwood, Metra
Electronics Corporation,
Pioneer Electronics,
Scosche Industries,
and Vehicle Security
Electronics for their
continued support
of the program and
contributions to
this book.
CONTRIBUTING COMPANIES
Alpine Electronics
ATX Research
Audio Comp Electronics, Inc.
Audio Control
Audivox
Benjamin Consulting
Bobit Publishing
Car Audio Engineering
CMA School of Mobile Electronics
Directed Electronics, Inc.
Installer Institute
JBL Car Audio
Listen Up
Luzerne County Community College,
Advanced Technology Center
Mobile Dynamics
Mobile One Auto Sound
Mobilworks
Ora Electronics
Pioneer Electronics
Quality Auto Sound
Robert Bentley Audio
Sherwood
South Bay Cellular Telephone Company
Stillwater Designs
Vehicle Security Electronics
Traffic Jams
MANAGING EDITOR
Chris Cook ..............................................MECP
DESIGN AND PRODUCTION
Alpha MicroDesigns, Inc. ........................http://www.amdi.com
CONTRIBUTORS
THE BASIC INSTALLER STUDY GUIDE
3
TABLE OF CONTENTS
INTRODUCTION
Understanding The Format ............................................................10
What Is MECP…And What Does It Mean To You? ........................11
Why Certification Is Essential: Customer Perceptions ....................11
Botton Line Benefits........................................................................11
Making The Most Of This Study Guide ..........................................12
Understanding The MECP Tests ....................................................13
How The Tests Are Created ............................................................19
Preparing For The Exam ................................................................20
The Day Before The Test ................................................................20
The Day Of The Test ......................................................................21
At The Test Site ..............................................................................21
How To Take The Test ....................................................................22
After The Test ................................................................................23
CHAPTER 1 - BASIC AND ADVANCED ELECTRICAL
Section 1 - Electrical Laws And Formulas For
The Mobile Electronics Environment ..................................................................26
Understanding OHM’s Law ............................................................28
Electrical Power ..............................................................................34
Series And Parallel Total Resistance Formulas ................................38
Kirchoff’s Voltage Law ....................................................................42
Kirchoff’s Current Law....................................................................42
Current Flow ..................................................................................43
Section 2 - Electrical Components........................................................................44
Resistors ........................................................................................44
Potentiometers................................................................................46
Inductors ........................................................................................47
Capacitors ......................................................................................48
Fuses And Circuit Breakers ............................................................51
Section 3 - Basic Electrical Troubleshooting..........................................................52
Voltage Drops ................................................................................52
Voltage Drops - Series Circuits........................................................54
Ground Loops ................................................................................55
Short Circuit ..................................................................................57
Open/Closed Circuits ....................................................................58
Clipping ........................................................................................58
Section 4 - Filters ................................................................................................60
Passive Crossovers ..........................................................................60
Bandpass Filters..............................................................................62
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THE BASIC INSTALLER STUDY GUIDE
TABLE OF CONTENTS
Section 5 - Relays, Batteries And Cable ..............................................................62
Batteries..........................................................................................67
Cable Quality..................................................................................68
Section 6 - Semiconductors ..................................................................................71
Transistors ......................................................................................71
Diodes ............................................................................................72
Section 7 - Automotive, Electrical and Charging Systems ....................................75
Ignition Switch Functions/Power Wiring ........................................76
Section 8 - Troubleshooting Guide ........................................................................77
Overall............................................................................................77
Speakers ........................................................................................78
Sample Test Questions ................................................................................80
CHAPTER 2 - INSTALLATION KNOWLEDGE & TECHNIQUE
Section 1 - Basic Installation Practices ................................................................84
Vehicle Check In ............................................................................84
Bookkeeping ..................................................................................85
Vehicle Disassembly And Reassembly ............................................86
Cable Routing/Lead Dress ..............................................................87
Power Accessing ............................................................................88
Ground Loops/Ground Paths..........................................................89
Finding A Good Ground ................................................................90
Proper Wire Gauges........................................................................91
Proper Connections ........................................................................92
Antennas ........................................................................................94
Fusing And Circuit Breakers ..........................................................95
Section 2 - Noise Troubleshooting ........................................................................96
System Noise ..................................................................................96
Types of Noise Problems ................................................................97
Section 3 -Battery Troubleshooting ......................................................................100
Hydrometer ....................................................................................102
Load Testing ..................................................................................102
Section 4 -Meters And Test Equipment ................................................................103
DMMS And VOMS ........................................................................103
Test Lights ......................................................................................109
Noise Sniffers..................................................................................109
Section 5 General Installation & Equipment........................................................103
Non-Powered Hand Tools ..............................................................111
Powered Hand Tools ......................................................................112
Large Shop Tools ............................................................................113
Specialty Tools ................................................................................113
Cutting Techniques ........................................................................114
TABLE OF CONTENTS
THE BASIC INSTALLER STUDY GUIDE
5
Margin Notes
Section 6 - Shop Safety ........................................................................................115
Safety Practices ..............................................................................116
Safety Around Batteries ..................................................................117
Safe Tool Use ..................................................................................117
Fire Extinguishers ..........................................................................118
Cleaning The Shop ........................................................................118
First Aid ........................................................................................119
Section 7 - Troubleshooting Guide ........................................................................119
Overall............................................................................................119
Noise Problems ..............................................................................120
Sample Test Questions ................................................................................125
CHAPTER 3 - INTRODUCTION TO AUTOSOUND,
SECURITY, WIRELESS & NAVIGATION
Section 1 - Introduction To Audio - Autosound Basics ..........................................130
Frequency ......................................................................................131
Wavelength ....................................................................................132
Period ............................................................................................132
Amplitude ......................................................................................133
Phase & Polarity ............................................................................134
Resonance ......................................................................................138
Frequency Response ......................................................................138
Octives and Harmonics ..................................................................141
Signal To Noise ..............................................................................142
Dynamic Range Of A Music Recording ..........................................143
Headroom ......................................................................................143
Section 2 - Introduction To Security ....................................................................144
Basic Components Of A Security System ........................................145
Sirens..............................................................................................146
Switch Triggers ..............................................................................146
Sensors ..........................................................................................147
Sound Sensors ................................................................................149
Engine Disables ..............................................................................150
Remote Controls ............................................................................151
Accessory Output Devices ..............................................................152
Telematic Systems ..........................................................................153
Basic Installation Tips ....................................................................154
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THE BASIC INSTALLER STUDY GUIDE
TABLE OF CONTENTS
Section 3 - Wireless Communications: The Basics Of Installation ........................156
Transceivers ....................................................................................156
Microphone ....................................................................................158
Permanetly Installed Antennas........................................................158
Hands Free Capability And Installation Kits ..................................161
Programming ..................................................................................162
Section 4 - Navigation Basics ..............................................................................162
Types Of Navigation ......................................................................163
Mounting The Monitor ..................................................................167
Wiring ............................................................................................167
Vehicle Speed Sensor Testing And Verification................................168
Testing The System ........................................................................170
Sample Test Questions ................................................................................171
Margin Notes
GLOSSARY OF TERMS
Glossary of Terms........................................................................................176
Appendix ....................................................................................................200
Reference Materials......................................................................................206
INDEX
Index ..........................................................................................................210
TABLE OF CONTENTS
THE BASIC INSTALLER STUDY GUIDE
7
INTRODUCTION
INTRODUCTION
The objective of the MECP Study Guide is to prepare you to become a Certified
Installer in your area of expertise. Put simply, this book provides you with the
answers to the questions that are asked in the Basic Installer Test and the
related sections of the First Class test. The Basic Installer Study Guide will also
give you the information needed to study for the Advanced Electrical and
Installation Knowledge & Technique portions of the First Class test. Whether
you’re trying to pass the Basic Installer, First Class, or Master Installer exam,
this guide will provide you with a firm foundation to build on for your Mobile
Electronics Education.
INTRODUCTION
Margin Notes
UNDERSTANDING THE FORMAT
For some people, sitting down and reading a study guide is not very rewarding…
or informative. In fact, it can be downright frustrating.
We realize that…but at the same time, we also recognize the importance for excellence in our industry. So in that vein, we have created a Study Guide that is informative and educational – and above all, easy to use!
Why? Because we want to see you succeed – because your professional performance reflects positively on everyone in the industry. In addition, it also helps you
and your company maintain a high level of customer satisfaction – and that can
translate into repeat and referral business.
Here’s how we made this book easier to use:
For example, important facts or key terms are printed in bold type so they stand
out on the page and are easy to locate. In addition, important notes are placed in
the margins.
Here’s how this book is formatted:
Margin Notes with the ✍ symbol are key points taken directly from the
text. They emphasize material that you’ll find in the Installer and First Class
tests.
■
■
Illustrations are included to reinforce important concepts.
■ Bold type alerts you to an important fact or key term. Many of these are
included on the test, so make sure you clearly understand their meaning.
Glossary is located at the back of the book. This is essential study material for any of the test levels.
■
Sample Test Questions are at the end of the section. These sample questions let you gauge your progress while preparing you for the test.
■
■ Key Formulas and equations are at the back of the text. They help you
understand and memorize the equations included in the test.
10
THE BASIC INSTALLER STUDY GUIDE
INTRODUCTION
WHAT IS MECP…AND WHAT DOES IT MEAN TO YOU?
Margin Notes
MECP stands for the Mobile Electronics Certified Professional Program. It was
designed and developed by the Education Committee and Certification
Committee of CEA – the Consumer Electronics Association, which is a non-profit
organization dedicated to the Consumer Electronics industry and is a sector of the
Electronic Industries Alliance (EIA).
The purpose of this certification program is to foster a level of professionalism and to achieve a level of knowledge.
■
MECP is also a learning and educational tool that allows installers of all
levels – through continued study and daily experience – to grow to the next
level of expertise.
■
MECP is a network of schools, manufacturers, retailers, installers, and
concerned industry professionals from the U.S. and Canada whose primary
goal is to help make this industry educationally sound with ongoing testing
and training.
■
WHY CERTIFICATION IS ESSENTIAL: CUSTOMER PERCEPTIONS
When a customer makes a commitment to upgrade their car audio, security, navigation or wireless system, they’re looking to your company to provide them with
the professionalism and service that accompanies their purchase decision.
Today’s customers are more demanding than ever before – they expect OEM
quality on their installations. Accordingly, you need to keep pace with the latest
techniques to ensure the “final product” lives up to your customer’s expectations.
■
In the automotive industry, there’s a statistic – a happy, satisfied customer tells 5
friends about their positive experience; but an unhappy, dissatisfied customer tells
15 - 20 people about their negative experience. A few dissatisfied customers can
quickly wipe out the good reputation of a company
■
BOTTOM LINE BENEFITS
MECP certification has its benefits:
■ Demonstrates your commitment, dedication and professionalism.
■
Assures consistent quality.
■
Qualifies the people who do the work.
■
Demonstrates a “we care” attitude.
■
Reinforces the quality of your operation.
INTRODUCTION
THE BASIC INSTALLER STUDY GUIDE
11
Margin Notes
MAKING THE MOST OF THIS STUDY GUIDE
First and foremost – this is not a “How To” book! It is a study guide – written
specifically for installers who wish to become certified professionals.
Here’s how you can make the most of this information:
■ Take notes – write in the margins (that’s why they’re there).
■
Study additional sources of information to round out your knowledge.
This is not meant to be the definitive source for installation instructions;
refer to the appropriate manufacturer’s publications for actual installation
information.
■
If you’re taking the basic Installer test level, you need to study:
■ All of the sections on Basic and Advanced Electrical and Installation Knowledge
and Technique (Study Guide 1 – Bronze level), as well as chapter 3 and the
Glossary definitions. It is important that you know the basics, and have good
knowledge of the technologies that you will be working with.
If you are taking the First Class test, you need to study:
■ All of the sections on Basic and advanced electrical, Installation Knowledge and
Technique, and Chapter 3 on Basics of Autosound, Security, Wireless & Navigation
(Study Guide 1 - Bronze level) as well as the entire First Class Study Guide
(Silver level) and the related Glossary definitions. It is important that you
know the basics, and have a good knowledge of the technologies that you will
be working with.
If you are taking any of the Specialist test, you need to study:
■ All of the sections on Basic and Advanced Electrical and Installation
Knowledge and Technique (Study Guide 1 – Bronze level).
The information that relates to your area of specialization –Autosound, or
Security.
■
If you are taking the Master Installer test, you need to know the theory behind all
these technologies:
■ This is the most challenging test; accordingly, you need to study all the
MECP Study Guide levels (Study Guide 1,2, & 3 – Bronze, Silver, and Gold)
including the Glossary of Terms, as well as the other books referenced in the
back of the Master Installer Study Guide (Study Guide 3 – Gold level).
12
THE BASIC INSTALLER STUDY GUIDE
INTRODUCTION
UNDERSTANDING THE MECP TESTS
Margin Notes
Here’s a breakdown of the different tests:
Installer Level
■
Basic Installer test – 150 questions; allotted time: 3 hours
1 Basic Electrical
2 Installation Knowledge and Technique
3 Tools and Shop Safety
4 Definitions and application of core technologies
The Basic Installer level tests basic electronics and DC knowledge and their applications to mobile electronics installations; basic knowledge pertaining to actual
installations and troubleshooting; sound, music, and product; basic working
knowledge and understanding of standard shop tools and safety procedures.
The Basic Installer certification examination is a basic level, 150 question multiple
choice and true/false examination broken down into three 50 question sections.
The questions within the three sections can be further broken down into the nine
categories listed below. The numbers in parentheses indicate the approximate percentage of the 50 question sections devoted to each subject matter.
Electrical Section Questions
1 Ohms Law (25-30%) - These questions require the knowledge of
Ohms Law formula and the math to solve a particular question. Many of
these questions require computation.
2 Electronic Components (45-50%) - These questions pertain to the physical electronic components such as capacitors, resistors, etc. This also
includes related topics like “farads” and “henries”.
3 Measurements & Applications (25-30%) - This classifies all questions
having to do with situations where knowledge needs to be applied and/or
measured in some form. This also includes the application of units and
scales such as dBs, amperes, etc..
Installation Knowledge and Technique Section Questions
4 Component Application and Usage (25-30%) - These questions pertain
to the actual way a component is used or applied in an installation. An
example is when (or when NOT to) install a noise filter or perhaps
whether an open or closed circuit is appropriate.
5 Troubleshooting and Analysis (50-55%) - These questions deal with the
diagnosis of incorrect installation procedures and/or components which
don’t operate properly.
INTRODUCTION
THE BASIC INSTALLER STUDY GUIDE
13
Margin Notes
6 Installation Techniques (15-20%) - This classifies all questions which
deal directly with physical installation related procedures and/or concerns.
Tools and Safety Section Questions
7 Measurement and Troubleshooting (50-55%) - This classifies all questions which directly address the measurement and troubleshooting of
12volt systems. This includes both the techniques and tools.
8 Power and Hand Tools (25-30%) - This classifies all questions which
deal with tools that ARE NOT considered measurement and troubleshooting tools.
9 Safety Practice and Safety Equipment (15-20%) - This classifies all questions which deal with safety and proper use of safety equipment
Specialist Level
■
Autosound Specialist test – 150 questions (50 questions/section);
allotted time: 3 hours
1 Basic and Advanced Electrical
2 Autosound Section
3 General Installation Knowledge
The Autosound Specialist certification examination is a first class level, 150 question multiple choice examination broken down into three 50 question sections.
The questions within the three sections can be further broken down into the eight
categories listed below. The numbers in parentheses indicate the approximate percentage of the 50 question sections devoted to each subject matter.
Electrical Section Questions
1 Ohms Law (20-25%) - These questions ask for and/or require the
knowledge of Ohms Law formula or math to solve a particular question.
Many of these questions require computation.
2 Electronic Components (45-50%) - This classifies all questions having
to do with the physical electronic components such as capacitors, resistors, etc.. This also includes related topics like “farads” and “henries”.
3 Measurements & Applications (30-35%) - These questions pertain to
situations where the knowledge needs to be applied and/or measured in
some form. This also includes the application of units and scales such as
dB’s, amperes, etc..
14
THE BASIC INSTALLER STUDY GUIDE
INTRODUCTION
Autosound Section Questions
4 Audio Theory and Analysis (40-45%) - This classifies all questions
which deal with both acoustic and electronic theory and analysis with
relation to sound in the mobile environment.
Margin Notes
5 Audio Components (30-35%) - These questions pertain to the physical
audio components which make up a mobile audio system. This includes
both passive and active electronic components as well as loudspeakers.
6 Installations and Testing (25-30%) - These questions deal directly with
physical installation related procedures and/or testing of a mobile audio
system. This includes subwoofer enclosure questions.
General Knowledge
7 Tools (45-50%) - This classifies all questions related to Tools. This
includes hand tools, power tools, measurement tools, and troubleshooting tools.
8 Safety and Installation Techniques (50-55%) - This classifies all questions which deal with safety and proper use of safety equipment. This category also classifies all questions which deal directly with physical installation related procedures and/or concerns.
■
Security Specialist test – 150 questions (50 questions/section);
allotted time: 3 hours:
1 Basic and Advanced Electrical
2 Security Section
3 General Installation Knowledge
The Security Specialist certification examination is a first class level, 150 question
multiple choice examination broken down into three 50 question sections. The
questions within the three sections can be further broken down into the eight categories listed below. The numbers in parentheses indicate the approximate percentage of the 50 question sections devoted to each subject matter.
Electrical Section Questions
1 Ohms Law (15-20%) - These questions ask for and/or require the
knowledge of Ohms Law formula or math to solve a particular question.
Many of these questions require computation.
2 Electronic Components (50-55%) - This classifies all questions having
to do with the physical electronic components such as capacitors, resistors, etc.. This also includes related topics like “farads” and “henries”.
INTRODUCTION
MECP PRODUCT SPECIALIST STUDY GUIDE
15
Margin Notes
3 Measurements & Applications (25-30%) - These questions deal with situations where the knowledge needs to be applied and/or measured in
some form. This also includes the application of units and scales such as
dB’s, amperes, etc..
Security Section Questions
4 Security Components (20-25%) - This classifies all questions which
pertain to the physical security components which make up a 12 volt
mobile security system.
5 Relays and Semiconductors (45-50%) - This classifies all relay and semiconductor questions as related to the installation of a 12 volt mobile security system.
6 Installations and Testing (35-30%) - These questions deal directly with
physical installation related procedures and/or testing of a 12 volt mobile
security system.
General Knowledge
7 Tools (65-70%) - This classifies all questions related to Tools. This
includes hand tools, power tools, measurement tools, and troubleshooting tools.
8 Safety and Installation Techniques (30-35%) - These questions deal with
safety and proper use of safety equipment. This category also classifies all
questions which deal directly with physical installation related procedures and/or concerns.
Specialist level exams are designed to test advanced electronics knowledge and
installation applications; and in-depth knowledge, understanding, application, and
troubleshooting in either autosound, or security. Note: To take this exam, MECP
requires notarized proof of one year’s work experience in mobile electronics.
■
First Class test – 150 questions total; allotted time: 3 hours
1 Autosound
2 Basic and Advanced Electrical
3 Security
First Class level exam is designed to test advanced electronics knowledge and installation applications; and in-depth knowledge, understanding, application, and
troubleshooting in autosound, wireless, security. Note: To take this exam, MECP
requires notarized proof of one year’s work experience in mobile electronics.
16
THE BASIC INSTALLER STUDY GUIDE
INTRODUCTION
The First Class certification examination is a 150 question multiple choice examination broken down into three 50 question sections. The questions within the
three sections can be further broken down into the nine categories listed below.
The numbers in parentheses indicate the approximate percentage of the 50 question sections devoted to each subject matter.
Margin Notes
Autosound Section Questions
1 Audio Theory and Analysis (20-25%) - This classifies all questions
which deal with both acoustic and electronic theory and analysis with
relation to sound in the mobile environment.
2 Audio Components (15-20%) - These questions pertain to the physical
audio components which make up a mobile audio system. This includes
both passive and active electronic components as well as loudspeakers.
3 Installations and Testing (55-60%) - These questions pertain directly to
the physical installation related procedures and/or testing of a mobile
audio system. This includes subwoofer enclosure questions.
Electrical Section Questions
4 Ohms Law (15-20%) - These questions ask for and/or require the
knowledge of Ohms Law formula or math to solve a particular question.
Many of these questions require computation.
5 Electronic Components (40-45%) - These questions pertain to the physical electronic components such as capacitors, resistors, etc.. This also
includes related topics like “farads” and “henries”.
6 Measurements & Applications (35-40%) - These questions cover situations where knowledge needs to be applied and/or measured in some
form. This also includes the application of units and scales such as dB’s,
amperes, etc..
Security Section Questions
7 Security Components (10-15%) - This classifies all questions which
pertain to the physical security components which make up a 12 volt
mobile security system.
8 Relays and Semiconductors (25-30%) - This classification includes all
relay and semiconductor questions as related to the installation of a 12
volt mobile security system.
9 Installations and Testing (55-60%) - These questions deal directly with
physical installation related procedures and/or testing of a 12 volt mobile
security system.
INTRODUCTION
THE BASIC INSTALLER STUDY GUIDE
17
Margin Notes
■
Master test – 180 questions total; allotted time: 3 hours
1 Advanced Electrical
2 Installation Knowledge and Technique
3 Advanced Autosound
4 Advanced Security
5 Troubleshooting
6 Glossary of Terms
Master Installer Level exam is the most advanced level test and is designed to test
installers in advanced electrical, autosound, security and troubleshooting. In
order to qualify to take the Master Installer exam, you will need a score of 70% or
better on all sections of the First Class test. Note: To take this exam, MECP
requires notarized proof of three year’s work experience in mobile electronics.
The Master Installer certification examination is MECP’s most advanced level. This
is 180 question multiple choice and true/false examination broken down into four
sections. The Electrical, Autosound and Security sections are each 50 questions,
and the Troubleshooting section contains 30 questions. The questions within the
four sections can be further broken down into the twelve categories listed below.
The numbers in parentheses indicate the approximate percentage of the question
sections devoted to each subject matter.
Electrical Section Questions
1 Ohms Law (20-25%) - These questions ask for and/or require the
knowledge of Ohms Law formula or math to solve a particular question.
Many of these questions require computation.
2 Electronic Components (35-40%) - This questions pertain to the physical electronic components such as capacitors, resistors, etc.. This also
includes related topics like “farads” and “henries”.
3 Measurements & Applications (35-40%) - This classifies all questions
having to do with situations where the knowledge needs to be applied
and/or measured in some form. This also includes the application of units
and scales such as dB’s, amperes, etc..
Security Section Questions
4 Security Components (10-15%) - These questions pertain to the physical security components which make up a 12volt mobile security system.
5 Relays and Semiconductors (30-35%) - This classifies ALL relay and
semiconductor questions as related to the installation of a 12 volt mobile
security system.
18
THE BASIC INSTALLER STUDY GUIDE
INTRODUCTION
6 Installations and Testing (50-55%) - This classifies all questions which
deal directly with physical installation related procedures and/or testing
of a 12volt mobile security system.
Margin Notes
Autosound Section Questions
7 Audio Theory and Analysis (25-30%) - These questions pertain to both
acoustic and electronic theory and analysis with relation to sound in the
mobile environment.
8 Audio Components (40-45%) - This classifies all questions which pertain to the physical audio components which make up a mobile audio
system. This includes both passive and active electronic components as
well as loudspeakers.
9 Installations and Testing (25-30%) - These questions deal directly with
physical installation related procedures and/or testing of a mobile audio
system. This includes subwoofer enclosure questions.
Troubleshooting Section Questions
10 Audio Related Troubleshooting (30-35%) - These questions pertain to
troubleshooting the AUDIO part of the system installation.
11 Security Related Troubleshooting (20-25%) - This classifies all questions
which pertain to troubleshooting the security and/or convenience items
in an installation.
12 General 12volt Electrical System Troubleshooting (40-45%) - This classifies all questions which deal with the vehicle troubleshooting including
audio and/or security components which may be causing problems or
interference with the vehicle electrical systems.
HOW THE TESTS ARE CREATED
The test questions are written and developed by:
■ A Committee of Master Installers.
■ Manufacturers’ trainers and subject matter experts.
■ Industry educators from schools and community colleges.
■ Testing and certification industry experts are used for content writing and
validation of each test.
The questions are designed to test your daily working knowledge of installation
technologies. Hands-on applications can only be tested and proven in a school or
work environment.
INTRODUCTION
THE BASIC INSTALLER STUDY GUIDE
19
Margin Notes
Most questions are multiple choice and some True/ False:
■ Multiple choice questions have four or five possible answers. Only one
answer is correct in every question.
PREPARING FOR THE EXAM
Some people get “test anxiety” and while they know all of the answers, they freezeup during the test.
That can be frustrating – but if you’re thoroughly prepared, the odds are on your
side that rather than feeling anxious…you’ll be ready to “ace” the exam.
Here are some easy steps that will help you to be fully prepared when you take
your exam:
■ Read the Table of Contents to find the sections you need to focus your studies.
Scan through the appropriate sections to get a “feeling” for how the information is organized.
■
■
Read each section – preferably three to four times.
■ Choose a time when you’re rested and fresh to study.
■ Note important topics or areas where you are weak in the margin.
■ Re-read each section a few days later until you feel you know the
information.
A week before the exam: re-read or review the chapter one more time to
refresh your memory.
■ In between reading the chapters, review the Glossary so you’re
familiar with the key terms and definitions.
■ Take the sample tests a few times:
■ You can take the sample test provided in the Study Guide or log on
to www.ce.org and select the Tech education and Services Section.
■ The first time “tests” your knowledge of the material.
■ Subsequent reviews familiarize yourself with the type of test you’ll
be taking.
■
THE DAY BEFORE THE TEST
■
Review each chapter and the sample questions.
■ Do not try to “cram” for the test the day before the test (it didn’t work in
high school…it doesn’t work here, either).
20
THE BASIC INSTALLER STUDY GUIDE
INTRODUCTION
If you have properly read this Study Guide, the information should already be
in your head and the correct answers will come to you quickly during the test.
■ Last-minute cramming can confuse you and make you even more
anxious about the test.
■
Margin Notes
Review each area you feel you may be weak in and review your notes in
the margins.
■
THE DAY OF THE TEST
■
Get plenty of rest the night before.
If you are coming straight from work, allow some extra time to relax and
unwind before you start the test (at least 15 - 20 minutes).
■ During that time, “clear” your head of the day’s activities.
■
■
Do not try to re-read the Study Guide at any time.
■
Stay relaxed and confident that you will do well on the test.
AT THE TEST SITE
Bring the following:
■ Two sharpened #2 pencils.
■ Your acceptance letter (if needed).
■ One form of photo identification.
Arrive at the test site on time or a little early:
■ Look in the lobby or front office for MECP signs or an events board that
directs you to the test location.
■
Check in at the room or designated testing area.
■ Have all of your information available to give to the proctor.
■
Take your test packet, sit down, relax, and wait for the proctor’s instructions.
■ Seating will be arranged every other seat, or at least an arm’s length
apart.
■ Each test is different from the person sitting next to you.
■
Listen carefully to the proctor’s instructions.
■ He or she will explain any last minute changes.
■ They will tell you how to fill out the scantron sheet.
■ They will also instruct you on how to hand the materials back to the
proctor when you are finished.
■
DO NOT MARK IN THE TEST BOOKLETS.
INTRODUCTION
THE BASIC INSTALLER STUDY GUIDE
21
Margin Notes
Any marks in the booklets cannot be permanently erased.
A mark, circled answers (right or wrong), or notes, will confuse the
next test applicant and could disqualify your score.
■
■
■
Do not talk during the test.
■ The appearance of cheating will immediately disqualify you from the test,
so make sure you follow the proctors directions in all areas.
■
No smoking is allowed in the test room.
■ If you must leave the room, do so quietly, leaving all your test materials
on the table.
If you have a question or there is a problem with your test booklet, raise
your hand or wait for the proctor to come to you.
■
■ Please be courteous to others taking the test, as you would expect them
to be with you.
■ Everyone wants to do well on the test and does not need
unnecessary distractions.
HOW TO TAKE THE TEST
It’s common to be anxious when taking a test – most people are. That can lead to
unnecessary, sloppy mistakes.
Here are some tips that will help you improve your performance:
■ Make sure that you neatly write your name on the scantron sheet – as you
would like it to appear on your certificate.
■
Read each questions twice before you look at the answers.
■
Do not attempt to “read into” a question.
■ There are no “hidden meanings” – so don’t ask the question, “What if?”
■ Answer the question as stated – leave all preconceived notions at
home…or in the install bay…on the day of the test.
Don’t skip around – answer the questions in sequence. (Can you imagine if
you tried to perform an installation out of sequence? You get the idea.)
■ If you come to a question that you cannot answer, mark the question number down on your scratch paper and come back to it after you
finish that section.
■ Be careful to keep your answers in numerical order – if you skip a
question, make sure you skip the answer on the scantron sheet or your
answers will be in the wrong place.
■
22
THE BASIC INSTALLER STUDY GUIDE
INTRODUCTION
Marking the scantron sheet:
■ Refer to the box on the front of the sheet on how to properly mark each
answer block.
■
Margin Notes
Use two or three hard strokes to darken the block.
■ Do not draw a circle, a dot, or make one soft line.
■ If the answer blocks are not marked properly, the scantron machine
will score improper marks as wrong answers.
■ Once you get into the rhythm of marking the answer blocks, you’ll find
that it’s easy to do correctly.
Be sure to erase all mistakes completely or the scoring machine could
mark your answer as wrong.
■
AFTER THE TEST
When you are finished:
■ Follow the instructions on page one of the test booklet and take your test
materials up to the proctor.
■
Leave the room quietly.
■ If you’re waiting for someone else to finish the test, wait in the lobby
or somewhere away from the test room.
■ Looking in the room to see if someone has finished, or waiting in
the hall outside the room, talking to other applicants, will only disturb
the others still taking the test.
You will receive your test results in four or six weeks of the test date.
Congratulations and Continued Success!
MECP
For testing dates and locations, call MECP: (703) 907-7689, or visit our web site
at www.ce.org and select Tech education and services.
INTRODUCTION
THE BASIC INSTALLER STUDY GUIDE
23
CHAPTER 1
BASIC AND ADVANCED ELECTRICAL
No matter your desires – whether professional or personal – before you can
start on any project, you need a solid grasp of “the basics.” Accordingly,
Chapter 1 forms the foundation of your entire MECP training. This chapter
introduces some basic principles of electronics, as well as some of the more
advanced formulas and laws.
Both the Basic Installer level and the First Class level Electrical section of
the MECP certification tests are included here. You should have a thorough
understanding of each topic before moving on to the next topic. For the First
Class level test you will need to study the complete First Class Study Guide
available from MECP.
1
BASIC AND ADVANCED ELECTRICAL
Margin Notes
It’s hard to imagine life without electricity. And while internal combustion engines
power our vehicles, it’s electricity that lights the stoplamp when you put your foot
on the brakes. And it’s electricity that powers the audio system.
The computer may be fueling today’s technological growth, but it was electricity
that started the revolution.
Therefore, before you can move into more specific areas of expertise, you first
need a solid foundation in electrical theory and application.
Section 1
Electrical Laws and Formulas for the Mobile Electronics Environment
What do “electrical laws and formulas” have to do with you - an installer?
Good question.
On the surface, it may seem like a plumber studying hydrodynamic physics - sure,
they both deal with the motion of fluids, but one is a little overkill.
The same theory does not hold true here.
Today’s installations are increasingly more complex - and the vehicles you are
working on are equally sophisticated. It is no longer just about hooking up the
components.
Being a mobile electronics installer truly is a profession - it requires skill and training,
and there’s always something new to learn. But before you can learn the “new stuff,”
you need to have a solid understanding of the basic electrical theories. That way, when
you encounter a particular challenge, you’ll know where to start troubleshooting.
After all, you can easily figure out when you’ve used the wrong size wire gauge or
have a bad connection without all that math cluttering your mind. But while handson experience is essential; understanding why a wire gauge is too small or what causes a bad ground will help you through many practical situations. A firm grasp of
electronics knowledge can guide you logically to the source of almost any problem.
Before getting to the mathematical relationships involved in electronics, you need
to know about the two types of electrical current you will be working with in the
mobile electronics environment - AC and DC.
■ “AC” stands for Alternating Current, which is current that alternates
polarity between positive and negative. AC has both an amplitude component (how much) and a frequency component (how often).
26
THE BASIC INSTALLER STUDY GUIDE
CHAPTER 1
BASIC AND ADVANCED ELECTRICAL
Margin Notes
“DC” stands for Direct Current, and it is current which supplies power to
electronic components and is EITHER positive OR negative in polarity, but
not both. DC has only an amplitude component (called potential) and a frequency of zero.
■
Alternating Current is an electronic current that periodically changes polarity
(i.e., it alternates from positive to negative).
■ In an alternating current circuit, the current flow reverses its direction on
each alternation. The voltage alternates from positive to negative and back
again to positive.
✍
Alternating Current is
an electronic current that
periodically changes polarity.
The rate of alternation (how often) is called frequency, which is measured
in cycles per second, or Hertz (Hz).
■
The number of times the AC signal cycles in one second is its specific frequency. Multiple frequencies blended together is how music is sometimes classified as AC.
■
On an oscilloscope, AC looks like this:
Amplitude
+
0
—
1 Cycle
■
Time
Figure 1. Oscilloscope., AC.
The other form of AC at work in the vehicle is the charging system. A key component of this system is the alternator. The alternator creates AC that is changed
into DC by a process called rectification, which allows the battery to charge.
✍ The alternator creates AC
that is changed into DC by
a process called rectification.
When it comes to the audio signal, we are concerned with the “AC” that flows from
the head unit through the signal processors, which is then amplified to drive the
loudspeakers. That audio signal contains many varied frequencies and amplitudes
which make up the tempo and pitch of individual sounds in music.
■ Alternating Current and music signals are covered in detail in the
AUTOSOUND chapter of the First Class Study Guide.
For now, most of our applications will focus on DC.
CHAPTER 1
BASIC AND ADVANCED ELECTRICAL
THE BASIC INSTALLER STUDY GUIDE
27
Margin Notes
✍ Direct Current is defined
as current that travels in
one direction only.
Direct Current is defined as a current that travels in one direction only. One terminal is always positive, and the other is always negative.
■ All things that rely on the vehicle battery as their source of power operate
with DC. This includes amplifiers, head units, security systems, radar detectors, car phones, and other electronic accessories. Sometimes a component,
though powered by DC, may output AC. This is the case with car amplifiers.
On an oscilloscope, positive DC looks like this:
+
ø
■
Figure 2. Oscilloscope., positive DC.
When analyzing electronic circuits, you’ll encounter the relationships between
these four electronic properties:
1
2
3
4
Voltage
Current
Resistance
Power
(E)
(I)
(R)
(P)
Ohm’s Law is the electrical formula that defines the relationship of these properties to each other.
UNDERSTANDING OHM’S LAW
✍
Ohm’s
Law
describes
a specific and measurable
relationship between current,
voltage, resistance and power.
Ohm’s Law is one of the most basic laws of electricity. Using mathematical formulas, Ohm’s Law describes a specific and measurable relationship between current, voltage, resistance and power.
Let’s look at these parameters and see how they apply to mobile electronics:
The properties that you need to understand are Voltage, Current, Resistance, and
Power. Power will be discussed later in this chapter.
28
THE BASIC INSTALLER STUDY GUIDE
CHAPTER 1
BASIC AND ADVANCED ELECTRICAL
Margin Notes
SYMBOL
PARAMETER
UNIT OF MEASURE
I
Current
Amps or Amperes
E
Voltage
Volts
R
Resistance
Ohms
P
Power
Watts
Ohm’s Law mathematically describes the interaction among these parameters.
Understanding the relationship among current, voltage resistance, and power can
help you figure out many different installation problems and answer many installation questions (even before the installation begins). For Example, Ohm’s Law will
tell you how much power an amplifier really puts out, if the voltage supplied to an
amplifier is too low, or if a higher power alternator should be considered. So lets
take a look at Ohm’s law and discover how it effects our work environment.
Current is the rate of electron flow through a given point, and is measured in Amperes or Amps. If you marked a point on a main road in a city
and counted the cars that pass that point in a specific window of time, you
could gain an understanding of the traffic flow on that road. A wider road
with more lanes would allow more cars to pass in a given window of time,
while a narrower road with fewer lanes would allow a smaller number of
cars to pass in that window of time. This illustrates the concept of current
flow in a wire or circuit.
■
Voltage is the electrical pressure that moves charged particles in a circuit,
and is measured in Volts. Voltage can be considered as the force of electricity. Voltage is also sometimes called difference of potential (potential difference) and, like the force of electricity, can be thought of as electrical pressure
that moves the current.
■
✍ Current is the rate of electron flow through a given
point.
✍
Voltage is the electrical
pressure that moves charged
particles in a circuit.
Just as the width of the road and number of lanes would effect traffic as we
described with current, a vehicle’s natural ability or potential to movement would
also affect traffic flow. A vehicle moving downhill could start and move much
more quickly than the same vehicle moving uphill. The natural force of gravity
assists that. Electrically, the natural force, (determined by potential) that moves
the charged particles through the circuit is much the same concept. More electrical pressure means more potential for electronic traffic flow.
What is the pressure exactly? How does it move the charged particles?
Let’s start to answer these questions by first defining some terms that relate
to voltage.
■
CHAPTER 1
BASIC AND ADVANCED ELECTRICAL
THE BASIC INSTALLER STUDY GUIDE
29
Margin Notes
■ Charge — or electrical charge is the fundamental unit for an amount of
electricity. Symbolized (Q).
Polarity — in an electrical circuit there are two different polarities: electrons posses a negative charge while protons posses a positive charge. It can
also be said that an electron has a negative polarity and a proton has a positive polarity.
■
■
Potential - refers to the ability to do work.
Now with these definitions let’s discuss some actions.
■ Like charges repel - two negatively charged particles held together will
repel or want to move away from one another. Likewise, two positively
charged particles held together will repel or want to move away from one
another.
Unlike charges attract - when two unlike charges are brought close together
they will attract or try to move toward each other.
■
These two reactions are proof of an electric field. Since potential is the ability of
the charges to do work, it’s the difference of potential (using the natural ability to
attract and repel) that allows the current to move and do work.
✍
Electrical
Resistance
describes the property that
various materials possess to
restrict or inhibit the flow of
electricity.
2
E
R
2
E
R
I •R
I•E
P•R
P
I
30
P
E
P/R
E R
E
I
2
I•R
P = Watts
I = Amps
■
The basic formulas used by Ohm’s Law to find current, voltage, or resistance are
as follows:
P I
P
2
I
Resistance is the opposition to current flow. To understand Resistance
think of anything that limits or blocks the flow of electrical traffic. Electrical
Resistance describes the property that various materials possess to restrict or
inhibit the flow of electricity. Electrical resistance is measured in Ohms (Ω).
Electrical resistance is relatively low in most metals and relatively high in
most non-metallic substances.
■
E
P
E = Volts
R = Resistance
I= E
R
E= IxR
R= E
I
Figure 3. OHM’s Law.
THE BASIC INSTALLER STUDY GUIDE
CHAPTER 1
BASIC AND ADVANCED ELECTRICAL
Margin Notes
According to Ohm’s Law:
If you want to find…
and you know…
then the math is…
Current (I)
Resistance (R) and Voltage (E)
E÷R=I
Current (I)
Power (P) and Voltage (E)
P÷E=I
Current (I)
Power (P) and Resistance (R)
(Sq.Rt.) √ P ÷ R = I
Voltage (E)
Power (P) and Resistance (R)
(Sq.Rt.) √ P x R = E
Voltage (E)
Current (I) and Resistance (R)
IxR=E
Voltage (E)
Current (I) and Power (P)
P÷I=E
Resistance (R)
Current (I) and Voltage (E)
E÷I=R
Resistance (R)
Current (I) and Power (P)
P÷I =R
Resistance (R)
Voltage (E) and Power (P)
E ÷P=R
Power (P)
Current (I) and Voltage (E)
ExI=P
Power (P)
Current (I) and Resistance (R)
RxI =P
Power (P)
Resistance (R) and Voltage (E)
E ÷R=P
2
2
2
2
Let’s take a less scientific approach to understanding the relationship between current, voltage, and resistance by comparing electrical characteristics to hydraulics.
Suppose you have a container of water. The pressure at the bottom of the container caused by the volume of water above it is similar to voltage. The more water, the
more pressure, the more voltage, the higher the difference of potential (voltage).
Container
of Water
Valve
On
■
Tube
Figure 4. Water Tank.
When the valve is opened, pressure forces the water through the pipe.
■ Voltage is like that “pressure” - only it is electrical pressure that is forcing
charged particles through a circuit.
■ If you were to open the valve wider, more water would flow through
the pipe.
■ If you were to make the valve opening smaller, less water would flow
through the pipe.
CHAPTER 1
BASIC AND ADVANCED ELECTRICAL
THE BASIC INSTALLER STUDY GUIDE
31
Margin Notes
This increase and decrease in the rate of water flow is comparable to the idea of
current, but remember that current is the rate of electrons that flow through a
conductor.
In addition, if you were to decrease the size of the pipe or bend it slightly, the rate
of water flow would decrease because you would be increasing the resistance.
■ This limitation in flow volume is similar to electrical resistance,
which restricts the flow of electrons.
The relationship between current, voltage, and resistance is similar to the container of water - change one parameter while leaving another alone and the third
has to change. It will always change according to Ohm’s law, which is the real
beauty in knowing this concept.
Understanding the relationship between current, voltage, and resistance can help
you figure out many different installation problems.
■ Ohm’s Law will tell you things such as:
■ How much power an amplifier really puts out.
■ If the voltage supplied to an amplifier is too low.
■ If a higher output alternator should be considered.
Let’s say, for example, that you’re powering up a high wattage audio system, but
you choose a wire that’s too small to supply the current required by the system.
The resistance in the wire will develop an unwanted voltage drop across it
(E = I x R) when the amplifiers draw power. Amplifiers operating with low voltage may overheat, motorboat, or fail.
An easy way to memorize Ohm’s Law is to use the Ohm’s Law Pie Chart. Simply “cover
up” the letter you wish to find the value of and carry out the remaining formula.
E
I R
Figure 5. OHM’s Law Pie
Chart.
■
Here’s another example of how useful Ohm’s Law can be in every day installations:
■ Suppose you have a resistor with a known value of 8 Ohms (R = 8), and
you know the current value that flows through the resistor is 1 Amp (I = 2).
What is the voltage across the resistor?
Simply apply Ohm’s Law:
R=8
I=2
E=IxR
E=2x8
E = 16 Volts
32
THE BASIC INSTALLER STUDY GUIDE
CHAPTER 1
BASIC AND ADVANCED ELECTRICAL
The following circuits show examples of how these formulas can be applied to
installations. Use what you’ve learned so far about Ohm’s Law to calculate the current, resistance, and voltage.
Margin Notes
1 How much CURRENT will flow through this circuit?
■
Figure 6. Current Circuit.
2 What is the RESISTANCE of an alarm siren when 12 Volts causes 11/2
Amperes to flow?
■
Figure 7. Resistance Circuit.
3 How much VOLTAGE is supplying this circuit?
■
Figure 8. Voltage Circuit.
The answers are:
1 2 Amperes
2 8 Ohms
3 4.8 Volts
CHAPTER 1
BASIC AND ADVANCED ELECTRICAL
THE BASIC INSTALLER STUDY GUIDE
33
Margin Notes
✍ Effective resistance is the
“calculated” resistance that a
device presents to a circuit
while it is operating.
Ohm’s Law is also very practical to know when you’re trying to calculate effective
resistance.
■ Effective resistance is the “calculated” resistance that a device presents to a
circuit while it is operating.
Knowing how to apply Ohm’s Law to determine resistance is practical because it’s
fairly easy to use a VOM (Volt Ohm Meter) to measure current and voltage, but
you cannot directly measure resistance in a live circuit.
For example, if you have an amplifier that draws 50 Amps, with an applied voltage of 12 Volts, for full power output with both channels driven into a 4 Ohm
load. How would you determine the effective resistance of the amplifier by applying Ohm’s Law?
Since we know that I = 50 Amps, and E = 12 Volts, we can manipulate Ohm’s Law
so that R is the isolated variable.
■
Simply divide both sides of the equation by I:
E=IxR
E=IxR
I
I
R=E
I
Now, insert the known values into the formula:
R eff = 12V
50A
R eff = 0.24 Ohms
ELECTRICAL POWER
✍ Power is the conversion
of energy into work over
a certain period of time.
✍ A watt represents the rate
over time that the energy is
Ohm’s Law relates a fourth circuit parameter - Power.
■ Electrical POWER is the conversion of energy into work over a certain
period of time, and a watt represents the rate over time that the energy is
converted. It’s the result of the collective work of current, voltage, and resistance. The last parameter, “P”, allows you to determine how much a system
can produce, how many amps it will draw, and therefore what gauge wire
and fuse size is needed. Power determines supply and demand.
converted.
34
THE BASIC INSTALLER STUDY GUIDE
CHAPTER 1
BASIC AND ADVANCED ELECTRICAL
Margin Notes
There are four basic forms of power:
■ Mechanical power, usually measured in horsepower.
■ Heat, measured in BTU’s (British Thermal Units).
■ Nuclear power, measured in Roentgens.
■ Electrical power, which is measured in Watts.
SYMBOL
P
PARAMETER
UNIT OF MEASURE
Power
Watts
✍ The law of Conservation
The law of conservation of energy states that energy cannot be created or destroyed,
only changed into some other form of energy. The same law is valid in audio circuits, where electrical energy is being converted into heat and sound.
of energy states that energy
cannot be created or
destroyed, only changed into
some other form of energy.
In more advanced studies of electronics, you’ll come across the terms coulomb
and joule.
■ A coulomb (pronounced koo-loam) is an electrical charge which contains
6.24 x 1018 of electrons.
✍ Coulomb is an electrical
charge which contains
18
6.24 x 10
of electrons.
18
A joule (pronounced jew-el) is the energy required to move 6.24 x 10
electrons (one coulomb of charge) past a point in a circuit.
■ If one coulomb of charge moves past the point every second, the
flow rate (current) is one ampere.
■
Since a watt represents the rate over time that energy (joules) is converted
into work (heat, sound, light, etc.), then a watt represents the conversion of
one joule per second into light, heat, sound, or some other form of work.
■
✍ Joule is the energy required
18
to move 6.24 x 10
electrons
(one coulomb of charge) past a
point in a circuit.
✍ A watt represents the
conversion of one joule
These definitions are not really necessary to know in every day installations; however, they help define the relationship between energy, power, and time.
Getting back to Ohm’s Law, electrical power is equal to volts times amperes, or
P = E x I.
■ One volt will move one amp through one ohm of resistance at a work rate
of one watt.
■
per second into light, heat,
sound, or some other form
of work.
Resistors convert electrical energy into heat.
CHAPTER 1
BASIC AND ADVANCED ELECTRICAL
THE BASIC INSTALLER STUDY GUIDE
35
Margin Notes
Remember that amperage is current flow per second, and therefore, a watt is rated
in seconds.
■ Since power equals: E x I, we know from Ohm’s Law that
E = I x R, P = I x R x I.
This is the formula we will use to figure out the power (wattage) for most
of our DC applications.
■
Here are some more ways Ohm’s Law can help you figure out different situations
(in addition, see the full Ohm’s Law pie chart in the back of this book):
■ How would you find the total current (I) of an amplifier at the electrical
system’s idle voltage?
Simply divide the amplifier’s total root mean square (rms) wattage (P) by
the vehicle’s idle voltage (E).
■ In a system with 250 Watts rms total audio output power,
(125 Watts rms/channel into 4 Ohms) and an electrical system with a
12.6VDC, the equation would look like this:
■
250 = 19.84 Amps
12.6
This can appear to be complicated - but if you focus on each element in the equation, then it’s easy to understand.
Here’s why it is important that you understand this equation:
■ It “tells” you what size wire to run from the battery to the amplifiers.
■ If the amplifiers are in the trunk.
■ You have a 15-foot cable run.
■ According to Figure 9, a #10 American Wire Gauge (AWG) cable is
necessary to adequately power up this system.
Ohm’s Law is indeed a very helpful tool to have in the bay.
36
THE BASIC INSTALLER STUDY GUIDE
CHAPTER 1
BASIC AND ADVANCED ELECTRICAL
Margin Notes
30
0
12
5
15
0
20 175
0
40
30
50
60
70
80
90
10
0
50
45
40
35
20
10
1.
5
75
15
Am
pe
re
s
100
40
0
30
25
20
15
12
10
20
■
18
16
14
12
10
8
6
4
Wire Size
2
1
1/0 2/0 3/0 4/0
Figure 9. Electrical Wire Chart.
POWER CABLE CALCULATOR
Total Amperage
Draw of System
Up to
4 Ft.
4 to
7 Ft.
7 to
10 Ft.
10 to
13 Ft.
13 to
16 Ft.
16 to
19 Ft.
19 to
22 Ft.
22 to
28 Ft.
0-20
14
12
12
10
10
8
8
8
20-35
12
10
8
8
6
6
6
4
35-50
10
8
8
6
4
4
4
4
50-65
8
8
6
4
4
4
4
2
65-85
6
6
4
4
2
2
2
0
85-105
6
6
4
2
2
2
2
0
105-125
4
4
4
2
0
0
0
0
125-150
2
2
2
0
0
0
0
00
The above chart shows wire gauges to be used, if no less than a .5 volt drop is accepted. If
aluminum wire or tinned wire is used, the gauges should be of an even larger size to compensate. Cable gauge size calculation takes into account terminal connection resistance.
■
IASCA’s Recommended Minimum Wire Gauge Size.
Using the same example and applying it to IASCA rules - an international sanctioning body for sound-off events - you derive a much different answer.
■ The first formula is perfectly adequate for a system to operate safely.
■ In an effort to compensate for the power wasted by the amplifier,
IASCA tends to overstate what is necessary for power conductors.
CHAPTER 1
BASIC AND ADVANCED ELECTRICAL
THE BASIC INSTALLER STUDY GUIDE
37
Margin Notes
IASCA uses the following formula:
250 x 2 = 500 (Watts)
500 (Watts) = 39.68 Amps
12.6(Volts)
According to the IASCA wire table, this would require a #4 gauge AWG cable.
For a 2 Ohm load, multiply by 2 again, as follows:
250 x 2 x 2 = 1,000 (Watts)
1,000 (Watts) = 79.37 Amps
12.6 (Volts)
This would require a #2 gauge AWG cable.
Whatever method you use, it is important to correctly identify the proper wire
gauge to use in the installation.
As a Mobile Electronics Installer, it is important for you to understand not only
Ohm’s Law as a concept, but also its applications to everyday installation. Ohm’s
law can figure out complex answers to installation questions by using the building blocks of current, voltage, resistance, and power. The facts don’t lie. Ohm’s
Law can provide real answers to many mobile electronics questions. Now that we
have covered Ohm’s Law, its time to move to more advanced formulas.
SERIES AND PARALLEL TOTAL RESISTANCE FORMULAS
One of the more important calculations you’ll make is to figure out how much of
a load speakers will present to an amplifier.
When designing a system, it is sometimes necessary to connect circuit components
- such as speakers, inductors and capacitors - in series or parallel combinations.
■ There are occasions when combinations of multiple subwoofers in single
or dual voice coil models could be optimum or be potentially damaged
depending on the method of connection.
✍ Series and parallel
combinations will have
an effect not only on the
source, which they are
connected to, but on
another as well.
38
■ Series and parallel combinations will have an effect not only on the source
which they are connected to, but on one another as well.
■ It’s common practice to connect two loudspeakers in parallel.
■ When these “paralleled” speakers are connected to the amplifier, the
combined speaker load will have a significant effect on how that amplifier performs.
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Therefore, understanding how series and parallel circuit relationships work is
another useful tool, especially when you’re building crossover networks, installing
multiple subwoofers, or performing system analysis.
Margin Notes
The drawing below shows resistors wired in parallel:
■
Figure 10. Resistors wired in parallel.
A series circuit is established when circuit components are connected in a string
- end to end - so only one common terminal is shared between two components.
Series circuits share current and divide voltage.
■ When resistors are connected in a series, the total resistance is the sum of
the resistance of each component.
■ For example, when you’re trying to figure out the total resistance
(Rt) of a series circuit, simply add up the numbers.
✍ A series circuit is established when circuit components
are connected in a string, end to
end, so that only one common
terminal is shared between
two components and they
share the same current.
Resistance in a series circuit is additive, and the formula looks like this:
Rt = R1 + R2 + R3…etc.
In schematic form, it looks like this:
+
Resistor #1
#2
#3
Rt =Total Resistance
Rt =R1 + R2 + R3
■
Figure 11. Series Network.
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THE BASIC INSTALLER STUDY GUIDE
39
Margin Notes
✍ A parallel connection
exists when circuit elements
Figuring parallel-total resistance formulas is a little more difficult.
A parallel connection exists when circuit elements are connected so that two terminals are shared and voltage is common across the shared terminals. Parallel circuits share voltage and divide current.
are connected so that two
terminals are shared and
voltage is common across
When two devices (resistors, for example) are connected in parallel, the formula
is as follows:
the shared terminals.
Rt = R1 x R2
R1 + R2
In schematic form, it looks like this:
Resistor #1
R1
Resistor #2
R2
+
-
■
Rt = R1 X R2
R1 + R2
Figure 12. Parallel Circuit.
Assuming that we have a 4 Ohm and an 8 Ohm resistance (similar to common
speakers resistance):
Rt = R1 x R2
R1 + R2
Rt = 4 x 8
4+8
Rt = 32
12
Rt = 2.67 Ohms
40
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Schematically, a parallel circuit with more than two resistances looks like this:
■
Margin Notes
Figure 13. Parallel Circuit with more than two resistances.
If more than two resistances are wired in parallel circuit and need to be figured
into the total resistance, use the following formula:
1
R =
1
R1
1
R2
1
R3
+ …
1
RN
This formula can look complicated, but is easily accomplished with a calculator.
Let’s say we are trying to solve a parallel circuit with three resistors: a 4 ohm, a 6
ohm, and an 8 ohm. Using the calculator’s 1/X function we can solve the equation
in this manner.
(4) (1/X) + (6) (1/X) + (8) (1/X) = (1/X) = Answer
(The 1/X function takes 1 and divides it by the value of the resistor or answer. Your calculator might use the X-1 function instead, it does the same thing as 1/X.)
To figure the parallel resistance of two speakers when both are the same impedance, simply divide one of the speaker’s resistances by two.
■ Remember, when devices are wired in parallel, the total resistance is
always less than the resistance of the component with the smallest value.
Always keep this in mind: The wiring of automobile, audio, cellular, and security
systems are in parallel with the car’s battery, and they are powered by the battery.
■ Current flows through the system from the positive battery terminal to the
power input of the system, through the system, through the body of the car,
then it goes back to the negative terminal of the battery.
✍ Remember, when devices
are wired in parallel, the total
resistance is always less than
the resistance of the component with the smallest value.
■ Each of these systems also has a power switch that is wired in series ultimately from the battery’s positive source to the equipment.
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THE BASIC INSTALLER STUDY GUIDE
41
Margin Notes
Series and Parallel Capacitors (to clarify the one exception to the rule)
■ Series Inductors and Resistors use the above formula for SERIES WIRING.
The same SERIES FORMULA applies to PARALLEL CAPACITORS.
■ Parallel Inductors and Resistors use the above formula for PARALLEL
WIRING. The same PARALLEL FORMULA applies to SERIES CAPACITORS.
KIRCHOFF’S VOLTAGE LAW
We’ve seen from some of the previous examples that single resistor circuit analysis can be figured out by using Ohm’s Law. More complicated circuit analysis,
however, requires an understanding of another important electrical law Kirchoff’s Voltage Law (KVL).
✍ Kirchoff’s Voltage Law
(KVL) states that the voltage
Kirchoff’s Voltage Law (KVL) states that the voltage applied to a DC series circuit must equal the sum of the voltage drops within the circuit.
applied to a DC series circuit
Vt = VR1 + VR2 + VR3.........( + Vn)
must equal the sum of the
voltage drops within the
circuit.
Where: Vt is the applied voltage, VR1 is the voltage drop across resistor #1, VR2 is the voltage
drop across resistor #2, etc. and Vn is the remaining voltage after all of the measured drops.
In other words, if you add up all the voltage drops across each individual component, the total equals the applied voltage.
■ This means that one volt dropped through wiring or connectors in a system will reduce the voltage to the equipment by one volt.
This is especially true in practical applications, for example in multiple speaker or
subwoofer (single and dual voice coil) installations.
■ Each speaker wired down the line to the same power cable would get a
little less power to it than the one before it.
Often overlooked, even in the simplest of installations, is that one bad
connection or poorly crimped terminal can affect the voltage for that series
section, but not for the whole system. That could explain all kinds of otherwise mysterious speaker behavior.
■
KIRCHOFF’S CURRENT LAW
Kirchoff’s Voltage Law will help you determine single loop circuits; however, solving parallel circuits which have multiple loops requires the use of Kirchoff’s
Current Law (KCL):
42
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This law states that the total current entering a point or junction in a circuit must equal the sum of the currents leaving that point or junction.
■
Margin Notes
✍ Kirchoff’s Current Law
It = IR1 + IR2 + IR3.........( + In)
Where: It is the total current, IR1 is the sum of current #1, IR2 is the sum of current #2,
etc. and In is the remaining current after all of the other measured currents.
Think of your power and ground connections as one big loop from and to the battery.
■ A heavy gauge ground wire is just as important, if not more so, as the power
wire gauge.
■ Too small a gauge ground wire will develop a voltage drop which
may also cause the amplifiers to overheat, motorboat, or fail.
states that the total current
entering a point or junction
in a circuit must equal the
sum of the currents leaving
that point or junction.
CURRENT FLOW
In the front part of this section, we covered many of the basic and advanced electrical laws you will need to know. Before we continue on to electrical components,
we need to clarify current flow.
There are two schools of thought on which direction current flows:
1 Conventional current flow - current flows from positive to negative
in the direction voltage drops across a resistor.
2 Electron flow - current flows in the direction that electrons flow from negative to positive.
✍ According to conventional current flow, current flows
from positive to negative in
the direction voltage drops
across a resistor.
✍ According to electron
Conventional
Current Flow
Electron Flow
flow, current flows in the
direction that electrons flow
from negative to positive.
+
+
Current
Battery
-
■
+
Resistive
Load
-
+
Current
Battery
-
Resistive
Load
-
Figure 14. Conventional current flow and electron flow.
Which theory is correct? Even the “experts” disagree:
Scientists generally analyze circuits with the scientifically accurate, but
harder to understand “electron flow” theory, which states that electrons travel from negative to positive.
■
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THE BASIC INSTALLER STUDY GUIDE
43
Margin Notes
■ Engineers analyze circuits with “conventional current flow” theory, where
current flows from higher voltage potential to lower voltage potential.
Either method - when properly applied - will result in the same answer when analyzing a circuit.
Section 2
Electrical Components
With those formulas in mind, let’s look at some of the electrical components you’ll
be using to improve system design and performance.
RESISTORS
✍ A resistor is an electrical
component designed to have
a specific resistance (or
opposition) to the flow of
electrons, measured in ohms.
For installers, the actual definition of a resistor is not as important as the concept
behind resistance. For test purposes, however, a resistor is defined as an electrical component designed to have a specific resistance (or opposition) to the flow
of electrons, measured in ohms.
The concept of resistance was introduced in Section 1. It describes the property
that some materials posses to restrict the flow of current.
■ Resistance is generally an undesirable characteristic in mobile electronics
wiring.
There are instances where an installer will use a resistor to introduce a
specific resistance.
■ Resistance can be added to a signal cable to reduce the input signal
voltage to an amplifier.
■ Power resistors can be used to reduce the amount of power to a
speaker (essentially changing the speakers sensitivity) to connect left
and right amplifier outputs into one speaker (center channel, rear mono
speakers), or to change the ohm load that a passive crossover sees.
■
Resistors come in all values and power ratings:
■ The most common values are between .1 and 10 million Ohms, with
power ratings of 1/8, 1/4, & 1/2 Watts for signal work, or 5, 10, 25 and up
to 1,000 Watts and higher for power work.
■ A resistor’s wattage rating indicates how much electrical energy can
be safely converted to heat.
CAUTION: All resistors can produce heat, and you want be sure that this heat does
not create a fire hazard.
44
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Remember that resistance is measured in ohms, and the color bands on the outside of
a resistor indicate its value. Figure 15 shows the color band system of resistors. Use
the Resistor Color Code Chart below to figure out the value of a particular resistor.
When you’re using a Digital Multimeter (DMM) or analog Volt-Ohm Meter
(VOM), resistance is measured on an R X (1,10, 100, 1,000) scale. Resistance values are expressed in Ohms Ω.
Multiplier
Multiplier
Tolerance
2nd significant figure
1st significant figure
Tolerance
Margin Notes
Failure Rate
2nd significant figure
1st significant figure
Resistors with black body are composition. non-insulated.
Resistors with colored body are composition. insulated.
Wire wound Resistors have the 1st color band double width.
■
Figure 15. Color Band System (Two Significant Figures).
RESISTOR COLOR CODE
Color
Black
Brown
Red
Orange
Yellow
Green
Blue
Violet
Gray
White
Gold
Silver
No Color
Significant
Figures
0
1
2
3
4
5
6
7
8
9
_
_
_
Multiplier
Tolerance
Failure Rate*
1
10
100
1,000
10,000
100,000
1,000,000
10,000,000
100,000,000
±20
±1
±2
±3
±4
_
_
_
_
_
_
0.1
0.01
±5
±10
±20
1.0
0.1
0.01
0.001
_
_
_
_
Solderable*
_
_
_
Troubleshooting Resistors - Troubleshooting resistive problems are pretty
straight forward since resistors almost always open when they go bad. An
open resistor in a series circuit will stop current from flowing in the circuit.
An open resistor in a parallel circuit will increase the circuit resistance and
decrease the total current.
■
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THE BASIC INSTALLER STUDY GUIDE
45
Margin Notes
✍ A potentiometer is an
adjustable or variable
POTENTIOMETERS
A potentiometer is an adjustable or variable resistor.
■ It has connection points at each end of the resistive material and has a
movable center contact known as a “wiper” that can be manually positioned
anywhere along the body of the resistive material between the two contacts.
A potentiometer is sometimes called a “pot” for short.
resistor.
Potentiometers have broad applications in this field:
■ In audio: to control volume, tone, and balance levels.
■
In security: to control sensor sensitivity.
As the wiper is adjusted, the ratio of resistance between the center contact and each
end contact is changed.
■ An audio signal applied to one end point and measured at the wiper will
change in level as the wiper is repositioned.
■ This is how volume and tone controls accomplish their missions,
and why they are sometimes called variable voltage dividers.
SINGLE-GANG
DUAL-GANG
A
1
2
WIPER
3
1
2
B
2
1
3
3
1
SHAFT
2
B
3
A
■
Figure 16. Common Potentiometers.
Troubleshooting Potentiometers - Troubleshooting or checking a potentiometer to see if it is good takes a few steps. Because a potentiometer has a mechanical feature we can not rule out its failure and must check its operation.
■
■ Since a potentiometer has three leads, and two leads are tied to the full
resistance, it can troubleshoot just like a typical resistor. The third lead is tied
to the wiper arm and traverses the length of the resistor element. The wiper
arm can be bent or broken and cause the resistance between it and either
other lead to be intermittent, infinite, or stationary when you try to adjust
the potentiometer.
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INDUCTORS
Margin Notes
An inductor is an example of an electronic component that possesses the property of inductance.
Inductance is the property that a component possesses that opposes any
change in current flow.
■ While resistance limits the flow of current in a circuit (regardless of
the frequency), inductance opposes any change in the current.
■
Think of an inductor as being like a flywheel. The flywheel has inertia, and once
it’s spinning at a certain RPM, it will resist any changes in RPM and continue to
spin at a fixed rate.
✍ Inductance is the property
that a component possesses
that opposes any change in
current flow.
Coils have this property of inductance. Therefore, inductors are coils of wire that
resist changes in the flow of current through them.
■ High frequency signals represent rapidly changing currents.
Therefore, inductors can be used to limit the strength of higher frequency signals, while still allowing lower frequencies to pass.
An inductor wired in series with a subwoofer allows the low frequency audio signal
to power the speaker but blocks the higher frequency signals, creating a low-pass
passive crossover.
■ In this case, AC is the audio output from an amplifier.
■
Different values of inductors establish different crossover frequency values.
■
Inductor values are measured in Henries.
✍ Inductor values are
■
1,000 Millihenries = 1 Henry.
expressed in Henries.
■
Millihenries are written simply as “mH”.
Figure 17. Inductor Symbols.
Top: Air-core.
Middle: Ferrite-core.
Bottom: Iron-core.
■
CHAPTER 1
BASIC AND ADVANCED ELECTRICAL
Figure 18. Ferrite-core
Inductor Construction.
■
THE BASIC INSTALLER STUDY GUIDE
■
Figure 19. Inductors (coils).
47
Margin Notes
Applying the series connection formulas we discussed in Section 1, when inductors are connected in series, the total inductance is the sum of the inductance of
each component:
Lt = L1 + L2 + L3... + Ln
When inductors are connected in parallel, the formula looks like this:
Lt = L1 x L2
L1 + L2
CAPACITORS
A capacitor is an electronic component that possesses the property of capacitance.
✍ Capacitance is the
property of an electronic
component that opposes
a change in voltage
across the component.
Capacitance is the property of an electronic component that opposes
change in voltage across the component.
■
Capacitors are constructed by separating two or more conductors - called
plates - with an insulator, called a dielectric.
■ A typical construction is two long strips of aluminum foil with plastic
sheeting between the foil sheets, which is wound up to minimize its size.
■ If an AC signal is applied to its plates, the current will flow through
the capacitor. What actually happens is that if an AC signal is applied
to the plates, the capacitor will charge one way (hence current flows),
then when the AC signal reverses direction the capacitor discharges
and then charges in that direction (again current flows), this action
makes it appear that AC current is flowing through the capacitor.
■ A DC voltage connected to the plates will not pass through the
dielectric, and no direct current will flow. This will appear to look like
an open circuit.
■
In the mobile electronics environment, capacitors have many uses:
■ They allow passage of high frequency energy (tweeter capacitors).
■ They store an electrical charge for use later.
■ They block the passage of DC (accessory noise suppression).
■ They attenuate low frequency energy (midrange capacitors).
✍ There are many types of
capacitors. The three most
popular are polypropylene,
Mylar, and electrolytic.
48
There are many types of capacitors. The three most popular are:
1 Polypropylene.
2 Mylar.
3 Electrolytic.
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Polypropylene and Mylar are known for their excellent sound quality and are used
for the higher crossover frequencies.
■ Most installers agree that the difference in sound quality between
polypropylene, Mylar, and electrolytic is minor in the lower frequencies.
Margin Notes
A capacitor wired in series with a tweeter and connected to an amplifier will allow
the amplifier’s high frequency signal to power the tweeter, while limiting the lower
frequency signals, thus creating a high-pass passive crossover.
Capacitor values are expressed in Farads.
Capacitance for mobile electronics applications is usually measured in
Microfarads (µF). 1 million Microfarads (µF) = 1 Farad.
✍ Capacitance for mobile
electronics applications
is usually measured in
Microfarads (µF).
■
Figure 20
■
■
■
Figure 21.
Figure 23
■
■
Figure 24
Figure 25
■
■
Figure 22
Figure 26
Figures 20 - 26. Various capacitors.
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THE BASIC INSTALLER STUDY GUIDE
49
Margin Notes
Regardless of type, all capacitors have a tolerance rating, which is stated as a plus
or minus percentage.
■ The smaller the percentage, the more accurate the crossover frequency.
Capacitors are also rated by voltage (maximum voltage applied).
■ This rating is very important to observe when constructing passive
crossovers, since the amplifier output (AC voltage) may be far higher 12
volts. Many capacitors used in passive crossover networks use 50v and 100v
ratings.
■ Other capacitors used for power applications might use 16v, 18v, 20v, or
24v ratings such as the input storage and filter capacitors in amplifier power
supplies and “stiffening capacitors” for example.
Some capacitors are “polar” electrolytic capacitors that have a negative and a positive terminal and must be installed in the proper electrical orientation.
■ These types of capacitors are not used in crossover work, but are used in
power supply circuits (such as a “stiffening capacitor”) or in noise suppression and filtering circuits on an automotive distributor, coil, or alternator.
Remember! For series and parallel combinations, the formula used to find total
capacitance is the opposite to that of a resistor or inductor.
In series, the formula looks like this:
CTOTAL
C1
C2
C3
Cn
1
CTOTAL =
1
C1
■
+
1
C2
+
1
C3
………
1
Cn
Figure 27. Capacitor Formula.
When capacitors are connected in parallel, the total capacitance (Ct) is the sum of
each component:
Ct = C1 + C2 + C3... + Cn
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FUSES AND CIRCUIT BREAKERS
Margin Notes
If installed properly, a fuse can save you a lot of time and headaches. Think of a
fuse as cheap insurance.
■ A fuse is simply a device that contains a wire or strip of metal which is
installed in series with a power line.
■ This strip of metal is designed to melt if it receives an excessive
amount of current.
✍ A fuse is simply a device
that contains a wire or strip
of metal which is installed in
series with a power line.
Fuses are used as a safeguard against circuit or system damage. For example, if you
have a customer who is a bit aggressive with the volume control of his stereo system, you can protect his tweeters from “blowing” by installing a fuse - in series with the tweeter.
To determine the proper amperage of the fuse, you’ll need to know the ohm load
of the tweeter as well as its continuous or nominal power rating.
■ The formula to find the amperage of the proper fuse is equal to the square
root of the continuous power handling, divided by the ohm load of the
tweeter.
Amperage = Square root of Continuous Power/Ohm load.
Sometimes you’ll run across a situation where the recommended fuse value is
higher than the largest available fuse.
■ You could install fuses in a parallel combination, but that can get bulky.
A circuit breaker works better in these situations, because like fuses, they
are designed to blow (or open) when the current becomes excessive.
■ A circuit breaker is different from a fuse in that it usually can be
reset. Circuit breakers that can be reset come as 2 types - Manual
Resetting or Auto Resetting.
■
A circuit breaker is a device placed in series with a power line which, when an
excess amount of current is sensed, will open the power connection, thus protecting a circuit or system.
For protection at the battery, use either a fuse or a circuit breaker. The idea behind
these devices is simply to open the circuit before any wires burn.
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BASIC AND ADVANCED ELECTRICAL
THE BASIC INSTALLER STUDY GUIDE
✍ A circuit breaker is a
device placed in series with
a power line which, when an
excess amount of current is
sensed, will open the power
connection, thus protecting
a circuit or system.
51
Margin Notes
Section 3
Basic Electrical Troubleshooting
Now that you’re familiar with many of the electrical components used in mobile
installations, it’s time to discuss common problems that occur when some of these
components fail or are improperly installed.
VOLTAGE DROPS
✍ A bad connection or any
point of resistance in the
power circuit will cause a
voltage drop.
In Section 1, you learned about resistance and how it opposes the flow of current.
■ When a device in a circuit has resistance, it will convert an amount of
energy into heat, which results in a certain amount of power loss.
■ This loss is commonly referred to as a voltage drop.
■ A bad connection or any point of resistance in the power circuit will
cause a voltage drop.
A drop in voltage can manifest itself in a variety of ways:
■ Voltage drops result in poor performance, which a customer could
attribute to a particular product.
■ Often, it has nothing to do with the product, but with the misapplication during an installation.
Here’s an example of the multiple possibilities for voltage drops to occur:
■ When a power window is activated, a circuit is completed.
■ This circuit starts from the positive “+” battery terminal and runs
through the key switch accessory terminal, the fuse block, and then
through the pressed window switch and one window motor lead.
■ It then runs out the other motor lead, through the un-pressed window switch, through the chassis ground and the metal of the vehicle,
and finally, through the battery ground strap to the negative terminal
of the battery.
In an ideal world, the load on the battery would be determined by the motor’s electrical characteristics.
In the real world, the motor determines most of the load unless there is a circuit
problem.
■ If a switch contact wears, or a connector corrodes, the motor may not
receive the power it requires.
■ The circuit problem prevents full power from reaching the motor;
some of the voltage that would normally go to the motor is lost across
a weak circuit connection or contact.
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Margin Notes
A loss can also occur if you install a window roll-up system and
make wiring connections with smaller gauge wire than that of the stock
wiring (See the figure below).
■
TO OTHER WINDOW
motor
M
motor
BATTERY
IGNITION KEY
VEHICLE CHASSIS
■
Figure 28.
■
Figure 29.
■
Figures 28 - 31 Power Window Circuits.
CHAPTER 1
BASIC AND ADVANCED ELECTRICAL
■
Figure 30.
THE BASIC INSTALLER STUDY GUIDE
■
Figure 31.
53
Margin Notes
VOLTAGE DROPS - SERIES CIRCUITS
In our discussion on series circuits, we mentioned that resistance in a series circuit is additive.
✍ Adding up the resistances
Adding up the resistances will give you the total resistance of the circuit.
will give you the total resis-
If the current flowing in a series circuit needs to be known (amperage), go back
to Ohm’s Law, I = E/R.
■ Current remains the same anywhere it’s measured in a series circuit.
■ Add the total series resistances together and divide by the voltage.
■ To find the voltage, or voltage drop, across each resistance in the circuit, use another Ohm’s Law, E = I x R.
■ Multiply the total circuit amperage times each individual device’s
resistance to obtain the voltage drop across that device.
tance of the circuit.
✍ The sum of the individual
voltage drops in a series
circuit must be equal to
the applied voltage.
Voltage in a series circuit is distributed among the devices in that circuit, according to their resistance. The sum of the individual voltage drops in a series circuit
must be equal to the applied voltage.
For example, in the following diagram, with an input voltage of 6 Volts, the voltage drop across each of the lamps is 2 Volts.
2 VOLTS
V
R = 10Ω
+
6 VOLTS
-
-
+
R = 10Ω
-
+
-
V 2 VOLTS
+
R = 10Ω
V
2 VOLTS
■
Figure 32. Electrical Diagram.
In a parallel circuit, as the next diagram illustrates, the voltmeter reading has
absolutely nothing to do with the value of the resistor, as the probes of the meter
are theoretically connected directly across the power supply.
12v
■
54
R1
2.2kΩ
R2
1.5kΩ
vm
R3
3.6kΩ
R4
4.7kΩ
vm
Figure 33. Electrical Diagram.
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GROUND LOOPS
Margin Notes
A ground loop is probably the greatest cause of noise problems in car audio.
■ A ground loop is more than one ground path where the differences in current potential of each path create a voltage differential.
■ This can allow alternator whine to enter the system, as well as other
problems.
A ground loop is created by any non-zero resistances between the wiring paths
used to ground or interconnect each piece of equipment. Even the frame of the
vehicle itself, which is the battery ground of the car, can have varying voltage differentials caused by current flowing through different circuit paths in the frame.
✍ A ground loop is more
than one ground path where
the differences in current
potential of each path create
a voltage differential.
✍ A ground loop is created
by any non-zero resistances
between the wiring paths
used to ground or intercon-
Chassis
Dash
+
nect each piece of equipment.
-
Battery
Antenna
Firewall
-+
RCA'S - +
Head unit
Amplifier
Chassis Fender
Chassis Body
■
Figure 34. Typical ground loops.
In today’s high powered audio systems, the supply current can easily be over 50
amps. Even a .01 Ohm resistance caused by a faulty crimp connection or corrosion
can develop up to a .5 volt drop, which could create a source for system noise.
The alternator produces pulsating DC voltage, and the battery filters out most but not all - of the ripple. Ripple is the residual AC left on the line after it has been
rectified into DC. The ripple is generally variable in frequency and determined by
engine speed (alternator spin).
Some ripple current will always be present on the supply line and the
chassis ground of the vehicle if the engine is running. The bigger the alternator output capability, generally the more ripple it will produce.
■ This can create noise in an audio system.
■ That’s why it’s extremely important to measure your ground points
back to battery ground and with each other.
■
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55
Margin Notes
■ Most good audio products have sufficient filtering on their +12 Volt
lines, but not on the ground side.
■ Multiple ground points to the frame can allow small voltage drops
to be created. Even the smallest voltage drop can carry alternator noise
on it because the frequency of the AC output of an alternator is within the audible range of your sound system.
Volts
Volts
12
12
12
0
■
Volts
Time
0
Time
0
Time
Figure 35. Ripple on +12VDC.
Single point - or single area - grounding is always preferable whenever possible.
■ Though it may not be practical to have a single ground point - unless the
radio, equalizer, and amplifier are in close proximity to each other - you
want to avoid long high current ground wire runs.
■ This can result in enough resistance to cause a ground loop.
A good ground point for the current drawing equipment - radio, equalizer, crossover, etc. - is at the firewall, and one good ground point for the high
current drawing amplifiers at the trunk will work. Make sure you have referenced the two ground points back to the battery and to each other, and
have no significant voltage drops (two-tenths of a volt or less).
■
Audio system wiring normally has higher resistance than the power system wiring.
■ The higher the resistance, the easier it is for the noise to enter.
■ Low quality, poorly shielded interconnect cables can easily allow
noise to enter the system.
■ This is also why high voltage, low source impedance headunits units
work well for noise rejection in addition to the other signal transmission advantages.
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SHORT CIRCUIT
Margin Notes
Since Kirchoff’s Voltage Law states that the voltages dropped in a series circuit must
add up to the supply voltage, if a piece of equipment is short circuited, or the
wiring becomes shorted out, the voltage dropped across it is reduced to 0 Volts.
■ Since the total of all voltage drops in a circuit must equal the supply voltage, more voltage must be dropped across the circuit’s wiring and connections.
The current in the circuit is equal to the supply voltage divided by the
total resistance.
■
✍ The current in the circuit
is equal to the supply voltage
divided by the total
resistance.
As the resistance approaches 0 Ohms, the current in the circuit increases
dramatically and often dangerously.
■ In automotive circuits, currents can easily be in excess of 200-300
Amps, resulting in melted wiring looms and electrical fires.
Educated installers wire fuses at the battery to protect their circuits from the expensive, catastrophic failures short circuits can
produce.
■ A short circuit will bypass any resistance (speaker, lamp) in a circuit
and cause it not to operate.
■
The following diagram shows a short circuit in operation. The voltage needed to
turn on the light bypasses it:
R
LAMP
= 8Ω
SHORT
CIRCUIT = 0Ω
■
Figure 36. Short Circuit Diagram.
Equate this with a power wire coming from a battery to trunk-mounted amplifiers
and the wire has no fusing at the battery.
■ The fuse at the battery is NOT to protect the amplifier, but to protect the wire.
■ This power wire could either be punctured by a screw when the sill
molding is put back on the vehicle, or pinched under the back seat.
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✍ The fuse at the battery is
NOT to protect the amplifier,
but to protect the wire.
57
Margin Notes
Using what you have learned so far, you can see that the equipment connected to
the wiring will be bypassed and will not operate.
■ To avoid a short circuit and severe damage to the car, ALWAYS FUSE A
POWER CABLE AT THE BATTERY AS CLOSE TO THE BATTERY AS
POSSIBLE, BUT AT A MINIUM OF 10 INCHES FROM THE BATTERY
TERMINAL.
IASCA rules require no more than 18 inches from the battery, but for the
purpose of this study we will use the MECP standard.
■
The same thing can happen to speaker leads.
■ When one is shorted to ground, the amplifiers may not work, or may give
the appearance of motorboating at about half volume.
■ Most modern amplifiers have “short stopping” ability, and the amp
can protect itself.
✍ An open circuit is a circuit
through which no current
can flow.
OPEN/CLOSED CIRCUITS
An open circuit is a circuit through which no current can flow.
■ Open circuits can be caused by something as obvious as a switch being off
(or open).
■ Open circuits can be caused by something not as visible, such as a light
bulb filament being burned out (open), the voice coil of a speaker being
open, or even corroded terminals.
■ In any event, in a series circuit, when one device becomes open, the
rest of the circuit will not work.
■ In parallel circuits, only that device which is open will not work
while the circuit voltage will still be available for the remaining devices.
Example of a series circuit: Certain types of Christmas tree lights in which the
whole string goes out if one bulb goes out.
Example of a parallel circuit: The lights in your home - if one light burns out, the
others remain operational.
✍ Clipping is usually caused
when a power amplifier is
driven into saturation.
58
CLIPPING
Clipping is distortion that’s usually caused when a power amplifier is driven into
saturation.
■ Saturation occurs when an amplifier’s input exceeds its operational limit.
■ Example #1: If a 12-Volt supply powered an amplifier with a gain of
30 to 1, a signal of 1/2 Volt peak-to-peak is applied to its input.
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The output would try to produce a signal of 30 times 1/2 Volt (15 Volts)
to the speakers.
■
Margin Notes
This 15-Volt signal could not be produced because the supply voltage is
only 12 Volts.
■
■
The output signal would be distorted (clipped) at the top and bottom.
■ Example #2: - If the output rails of the amplifier are (+) and (-) 20
volts and the gain setting is set for a gain of 10.
As long as the input signal was lower than (+) or (-) 2 volts the output
would be a non-distorted representation of the input.
■
■ Once the input went above that level, say (+) and (-) 2.5 volts (the amplifier would try to put out (+) and (-) 25 volts) the tops and bottoms above
the rails would be cutoff because the max output is (+) and (-) 20 volts.
This would look like a square wave on an oscilloscope as pictured in figure below.
■
NORMAL AUDIO SIGNAL
CLIPPED AUDIO SIGNAL
■
Figure 37. Normal and clipped audio signals.
Clipping - particularly at high frequencies - will burn out a tweeter’s voice coil.
■ Distortion, or clipping, will blow a tweeter faster than too much power or
too low a crossover point.
While it’s true that a respectable amount of power to handle the instant
demands of musical peaks and valleys is necessary for clipping-free operation, 200 Watts rms into a tweeter designed to take only 50 Watts rms will
eventually damage the voice coil.
■
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59
Margin Notes
✍ A filter is a component or
a combination of circuit components which select or limit
a signal as a function of the
signal’s frequency.
✍ Digital filters are commonly
used in Compact Disc players
to eliminate noise caused by
the sampling clock.
✍ Active filters are built with
components such as operational amplifiers or transistors
in circuits which require some
form of external power.
✍ Passive filters provide no
Section 4
Filters
Applied to mobile electronics, a filter is a component, or a combination of circuit
components, which select or limit a signal as a function of the signal’s frequency.
■ In the simplest of examples, they work like a coffee filter which allows the
coffee to pass through the filter, while stopping the ground coffee beans.
An electrical filter allows some frequencies to pass through the circuit
unchanged, while other frequencies are stopped (attenuated) by the filter.
■
Filters are used in numerous applications:
1 Digital filters are commonly used in Compact Disc players to eliminate noise caused by the sampling clock.
2 Active filters are built with components - such as operational amplifiers or transistors - in circuits which require some form of external power.
■ Active filters are used in many low level signal applications, such as
tone controls and equalizers.
3 Passive filters provide no amplification and are made of resistors,
capacitors, and inductors.
■ Passive filters are very effective for reducing engine noise, but the
most common use for passive filters are as crossover and equalization
networks.
amplification and are made
of resistors, capacitors,
PASSIVE CROSSOVERS
and inductors.
Passive crossovers are used in many applications in the mobile electronics industry, especially with today’s coaxial and triaxial speaker systems.
■ A passive crossover separates the amplified audio signal into selected frequency bands. These bands of frequency are then directed to a loudspeaker
that is designed for its reproduction.
■ A capacitor will send only the highs to the tweeter in a two-way
(coaxial) system, or to the mid and tweeter in a three-way system.
■ This is a passive crossover in its most simple application.
✍ A passive crossover
separates the amplified
audio signal into selected
frequency bands.
Using a passive crossover is the most efficient and least expensive way to design a
speaker system in which certain frequencies are directed to a tweeter (highs) or a
mid-bass driver (lows).
■ A passive crossover for a basic two-way system consists of one capacitor
for the tweeter and one inductor for the woofer.
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In a passive crossover for a three-way system, one coil goes in series with
the woofer; one coil and one capacitor go in series with the midrange; and
one capacitor goes in series with the tweeter.
■
Margin Notes
✍ A passive crossover for a
6 dB / Octave
6 dB / Octave
HIGH
L
L
+
W
AMP
sists of one capacitor for the
tweeter and one inductor for
+
the woofer.
M
AMP
–
–
LOW
C
+
+
basic two-way system con-
–
–
6 dB / Octave
C
+
+
T
AMP
–
–
■
Figure 38. A 6 dB passive crossover network.
The rate at which a passive crossover blocks or passes frequencies above or below
the crossover point is expressed in dB’s per octave.
■ This is usually shown as a crossover slope (6 dB, 12 dB, or 18 dB), or a
crossover order (1st order, 2nd order, or 3rd order).
✍ The rate at which a
passive crossover blocks or
passes frequencies above or
below the crossover point is
OUTPUT
expressed in dB’s per octave.
1st-order
2nd-order
3rd-order
20
■
200
2000
FREQUENCY (Hz)
20000
Figure 39. Different crossover orders.
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61
Margin Notes
✍ A bandpass filter incorpo-
BANDPASS FILTERS
A bandpass filter incorporates both high-pass and low-pass filters in order to limit
and attenuate both ends of a frequency range. It will pass signals with frequencies
above or below the “pass band.”
rates both high-pass and
low-pass filters in order to
limit and attenuate both
ends of a frequency range.
Tweeter
High-Pass
Midrange
Low-Pass
Band-Pass
Band-Pass
High-Pass
Woofer
Low-Pass
■
Figure 40. Typical crossover bands.
Section 5
Relays, Batteries and Cable
✍ A relay is an electromechanical device that
uses a coil (electro) to move
switch contacts (mechanical).
One of the most important electrical components is the relay.
■ A relay is an electromechanical device that uses a coil (electro) to move
switch contacts (mechanical); it really is nothing more than an electromagnetically controlled switch.
■ The coil can be energized with a small amount of power while the
switch contacts can be used for any number of applications, including
high power circuits or reversing the polarity of a control signal.
The most common applications of a relay are to provide:
■ Circuit isolation.
■ Signal inverting.
■ Increasing/decreasing current handling.
■ Logic level shifting.
■ Transfer switching.
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A relay is essentially made up of three separate sections:
1 An electromagnetic coil.
2 Movable contact(s).
3 One or more sets of stationary contact(s).
Margin Notes
Anything that can be done with a switch can be controlled by a relay.
■ The primary difference between a simple switch and a relay is that the switch
contacts of a relay are controlled by magnetic force (the relay coil), while the
contacts of a simple switch are controlled by manual force (your finger).
Switches, like relays, come in all varieties and types. The important specifications
of a switch are its:
■ Contact arrangement.
■ Current handling capability.
■ Switching characteristics.
■ Switching function.
These characteristics should be considered when you’re selecting a relay for a particular task.
Relays are often used in security system installations to control such things as:
■ Starter interrupts.
■ Door locking circuits.
■ Power window and sunroof circuits.
■ Flashing parking lights.
■ Power trunk/hatch releases.
■ Air horns.
■ Sirens.
■ Triggers.
■ Sensors.
■ Garage door openers.
A modern security system installation usually depends on several relays to make
everything work.
The main elements of a relay are the coil, the spring, and the contacts.
■ These elements determine how the relay is to be rated by the manufacturer and used by the installer.
■ A typical 12-Volt Bosch relay requires a coil current of .150 Amps to
energize. (Again, ohms law can be used to find the current which will change
slightly based on the voltage applied to the coil. Measuring the resistance and
dividing the voltage by the resistance will give you the current).
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✍ The main elements of
a relay are the coil, the
spring, and the contacts.
63
Margin Notes
■ The relay contacts can switch current up to their rated amperage
value, but in most of the mobile electronics applications we will use 30
to 40 amp ratings.
■ The power gain of this relay is as high as 200 to 1, and is one reason
relays are often found in high current automotive circuits.
■ In most circuits, a relatively weak control signal (or trigger) is used
to make the relay control a higher current or voltage circuit.
An alarm system’s output energizes the coil, which magnetically closes (or opens) the much heavier duty contacts, allowing the desired action to result.
Below is an illustration of the bottom of a Bosch relay (the brand we’ve chosen as
an example):
A schematic of a Bosch relay looks like this:
87
86
87a
85
30
SPDT
■
Figure 41. Bosch relay.
85
87
87a
86
30
SPDT
■
Figure 42. Bosch relay schematic.
The Terminals of a Bosch Type Relay are Defined as:
64
30
C
=
(Common)
87a
N/C
=
(Normally Closed)
87
N/O
=
(Normally Open)
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The relay Coil (85 and 86)
This is what is powered, either by a 12-Volt trigger to 85 (or 86) with 86 (or 85)
to ground, or with a negative trigger (common on alarm systems) to 85 (or 86),
and 12-Volt CONSTANT to the other pin (86 or 85).
■ Usually, it doesn’t matter whether pin 85 or 86 is used for ground or 12
Volt; either way will activate the coil.
■ Whenever the relay has an INTERNAL SPIKE SUPPRESSION
DIODE, 85 must always be the Negative (-) terminal and 86 must
always be the Positive (+) terminal. This is so that the diode functions
properly and protects the “driver” which activates the relay from the
reverse voltage that’s generated when the coil field collapses. This is the
case when many vehicle control computers activate relays. Most OEM
relays are wired this way. If you also get in the habit of using this method
it could help avoid surprise problems in future installations and aid in
the diagnosis of OEM related relay problems.
■ By using either of the above methods, the coil will magnetically actuate, opening contacts 30 and 87a, while transferring the circuit path by
closing 30 and 87.
■ This type of relay is known as a Single Pole Double Throw relay
(SPDT).
Margin Notes
✍ Whenever the relay has
an INTERNAL SPIKE
SUPPRESSION DIODE, 85
must always be the Negative
(-) terminal and 86 must
always be the Positive (+)
terminal.
30
Terminal 30 is common. One side of whatever is being controlled goes here.
30 and 87A
Normally closed (NC).
30 and 87
Normally open (NO).
87a
87
30
AT REST
■
87a
87
30
ENERGIZED
Figure 43. Bosch relay schematic.
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65
Margin Notes
In examining the relay in an electrical circuit, we can see that a conduction path
between contacts is physically transferred when the relay is energized.
■ With the relay not energized and at rest, a circuit exists between the movable contact assembly (the common contact) and the first stationary contact
assembly (the normally closed contact).
■ When the coil is energized, the pole piece moves the movable contact(s)
away from the first stationary contact assembly and physically switches the
movable contact(s) to the second stationary contact assembly (normally
open contact).
■ This movement of the pole piece transfers the circuit path from the
movable contact assembly to a second stationary contact assembly.
The following diagrams show the other types of commonly used automotive
relays:
85
87
87
87
86
87
85
30
86
30
SPST
SPST
86
87b
87
87
86
87b
85
30
85
30
SPST
■
66
SPST
Figure 44. Other types of automotive relays.
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BATTERIES
Margin Notes
The vehicle battery is a chemical energy storage device and the power source to start
the engine.
■ A battery has many purposes, but one common misconception is that it
is the primary source of electrical power while the vehicle is being driven.
■ In reality, once the engine is running, the alternator is the primary source
of electrical power while the vehicle is being driven.
■ Although batteries offer only direct current, alternating current is produced by the alternator. This AC is then rectified by diodes into direct
current to recharge the battery and supply the vehicle’s circuits with the
necessary power.
The following diagram shows a common automotive battery:
■
Figure 45. Automobile battery.
✍ The term rectification
refers to the process of
The term rectification refers to the process of changing AC to DC current.
changing AC to DC current.
The vehicle’s battery is sometimes referred to as the electrical system’s largest
capacitor. This is due to its characteristic of resisting any change in the voltage
across it, and to its ability to be discharged and recharged. These characteristics
enable it to smooth out transient ripple currents in a system.
✍ The vehicle’s battery is
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THE BASIC INSTALLER STUDY GUIDE
sometimes referred to as
the electrical system’s
largest capacitor.
67
Margin Notes
A car lead-acid type battery is made up of six cells.
■ In a fully charged 12-Volt battery with no load on it (open circuit), each
cell has a nominal voltage output of 2.11 Volts.
■ The battery fluid is called electrolyte, which is sulfuric acid and water.
■ When a circuit is powered by the battery, a chemical reaction takes
place inside the cells between its electrolyte and lead plates, and a current flow is established.
■ When the battery is recharging, the chemical reaction not only stops,
but is reversed, allowing the electrical charging energy to be chemically stored within the cells for later use.
■ The output power of a battery is determined by its energy storage
capacity (cold-cranking amps), and the ability of the battery to smooth
ripple currents is a function of both its internal resistance and capacity.
■ As a battery ages, its ability to filter ripple current (noise) decreases,
and its impedance increases. (See battery cutaway in back of book.)
■ Remember that the battery is an electro-chemical device and cannot
create current instantaneously, so as current is drawn voltage will
decrease.
Running a “new” standard car battery until it’s dead may result in the battery’s
reserve capacity being reduced by half.
■ Once an automotive lead-acid battery has been “deep-cycled,” it cannot
be recharged to its original specifications. Dropping the battery’s rated voltage by 25% is what is meant by deep-cycled.
✍ A “primary” battery can
store and deliver electrical
energy, but cannot be
recharged.
A “primary” battery can store and deliver electrical energy, but cannot be
recharged.
Lead-acid automobile batteries are “secondary” batteries.
■ A secondary battery can also store and deliver electrical energy, but unlike
the primary battery, recharging is possible by passing a direct current
through the battery in the opposite direction to that of the discharge.
CABLE QUALITY
Expert mechanical installation will be of limited value if you don’t use high-quality cable of the correct size for the electrical installation. Remember the water pipe
analogy in Section 1? This is a good way to think of signal (or current) flow
through speakers and power cables.
■ When a large amount of water has to go through a pipe which is too small,
it will take longer for the water to go through the pipe, and the full flow of
water is reduced.
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When a larger, proper sized pipe replaces the small pipe, the same volume
of water flows freely, with less resistance.
■
Margin Notes
Applying this example to electricity:
■ The pipe is the power cable, which experiences increased voltage drops if
it’s too small to carry the required current.
■
The water represents the current flowing.
■ If the wire is too small or too long, resistance is increased.
■ As resistance increases, the power cable will start to overheat. The
heat could melt the cable and create a hazard to the system and the
vehicle.
■ Also, as resistance increases, the power amplifier at the other end of
this small, overworked cable suffers a significant voltage drop. This will
not allow the amplifier to get the full voltage and the current it needs
to operate properly, which will diminish its output and could easily
cause distortion.
✍ As resistance increases,
the power cable will start to
overheat. The heat could melt
the cable and create a hazard
to the system and the vehicle.
Always remember to use the proper size (even slightly oversized) power, ground,
and speaker cables.
For power amplifier wiring, you will need sufficient AWG rating to handle the
current load (see IASCA chart in Section 1).
You will also need a high temperature, multi-strand cable. A flexible gas and oil
resistant outer jacket is also desirable. Never use solid wire in the high vibration
environment a vehicle creates.
A common misconception is that you can skimp on the ground cable.
■ The ground cable carries as much current back to its source (the battery) as
the supply cable, and should really have a gauge the same current potential of
the supply cable. Using the same size gauge wire (since the ground/chassis
connection is generally shorter) is a good practice to use.
✍ You will also need a high
temperature, multi-strand
cable. A flexible, gas and oil
resistant outer jacket is also
desirable. Never use solid
wire in the high vibration
environment a vehicle creates.
Knowing what voltage will be present at the amplifier end of the supply cable (i.e.,
battery voltage less voltage drop) is also important when selecting a proper gauge
power cable.
■ If you know the maximum amperage the system is going to draw and the
resistance per foot of cable, the voltage drop is easy to calculate.
Use what you know about Ohm’s Law to figure out the following formula:
E=IxR
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69
Margin Notes
If you are installing a system which has a 13-Amp draw and using
a AWG size #10 cable (assume that #10 cable has a resistance of .047 Ohms for a
20 ft. run), how would you find the voltage drop at the amplifier end of the cable?
E
(voltage)
=
I
x
R
(amperage)
(resistance)
E = 13 (Amps) x .047 (Ohms)
E = .61 Volt loss
Nearly two-thirds of a volt is lost between the battery and the amplifier. Think of
how this could affect peak amplifier performance!
When selecting speaker cables, shielded audio cables, and power cables, select
ones using deoxygenated, also known as oxygen-free, copper cable.
■ Deoxygenated copper has had nearly all the oxygen removed from the
copper during the manufacturing process. The result is less resistance (the
speaker, amplifier input, and the amplifier itself get more power), and the
wiring will not corrode and turn green as normal copper cable will over time
or if the vehicle is in a damp or salty environment.
There are four factors that determine the resistance of a cable:
1 The cross sectional area (i.e., the AWG size; the larger the cross-section, the lower the resistance).
2 The temperature of the conductor (higher temperature means higher
resistance).
3 The “resistivity” of the material the cable is made of (copper, deoxygenated copper, aluminum).
4 The length of the conductor (more wire length equals more resistance).
Although you cannot control the temperature of a cable, you can do a lot to control the other remaining factors.
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Margin Notes
Section 6
Semiconductors
TRANSISTORS
A transistor (transfer-resistor) is an electronic switch that can replace or enhance
a relay.
■ A more technical description of a transistor is a solid-state device in which
a large output current is controlled by small changes in the input current.
Transistors have three leads:
1 Collector.
2 Base.
3 Emitter.
✍ A transistor (transferresistor) is an electronic
switch that can replace
or enhance a relay.
✍ Transistors have three
leads: the collector, base,
and emitter.
Through different connections of these leads, a transistor can do most jobs of a
relay, particularly when signal inversion is desired.
Transistors come in two types:
1 NPN (the NPN silicon type transistor is the one most commonly used
in place of a relay).
2 PNP.
Both types are made from either silicon or germanium.
Capacitor (C)
M
J
E3055T
M 839
N
B C E
Base (B)
P
(C)
Capacitor
N
(B) Base
Emitter (E)
■
(E) Emitter
Figure 46. Three views of an NPN transistor.
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71
Margin Notes
When used as an amplifying component, transistors heat internally as they control the current in a circuit.
■ To dissipate this heat, the transistor is mounted to a heat sink, which
removes the transistor’s heat and disperses it over the area of the heat sink.
■ Always mount an amplifier in a manner in which it will dissipate
heat correctly, this can prevent premature failure of the amplifier.
■ CAUTION: The metal tab of the transistor can be a collector connection and, if so, is electrically wired into the circuit. In this case, do
not touch it or mount it directly to chassis metal; isolate it or insulate
it first before mounting or securing it in place.
DIODES
Because of their unique isolating capabilities, diodes are being used more and
more in the installation bay.
■ Diodes are perfect for isolating alarm systems from the factory electrical
wiring and are also effective for battery isolation and noise elimination.
✍ A diode is a two-electrode
(two-terminal) device which
allows current to pass through
it in one direction only.
A diode is a two-electrode (two-terminal) device which allows current to pass
through it in one direction only.
■ The two leads of a diode are the anode and the cathode.
■ A diode is the simplest of all semiconductors and can be thought of as a
one-way electron valve.
The following diagram is of a diode with the leads marked:
(N)
CATHODE
(N)
■
(P)
ANODE
(P)
Figure 47. Diode diagram.
When the positive terminal of the voltage source is connected to the anode, the
return circuit is connected to the cathode (making it more negative than the
anode), then current is flowing from negative to positive.
■ Here, the diode is said to be forward biased.
■ On a meter, it would read a low resistance.
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A diode connected in the reverse manner will not conduct electrons, but will measure a high resistance.
■ In this case, the diode is said to be reverse biased.
■ No current will flow in a circuit which has a reverse biased diode.
Margin Notes
In the previous diagram, the positive end (anode) is shown schematically as an
arrow. It’s important to memorize which is the anode and cathode because circuit
diagrams (schematics) will not tell you.
The following diagram shows forward biased:
(-)
(-)
(+)
NO OUTPUT
(+)
(+)
NO OUTPUT
■
(-)
Figure 48. Positive voltage applied.
Also, like transistors, pieces of “P” or “N” material are used to form the diode.
■ When a piece of N (negative) or P (positive) material is joined together, a
joint called the barrier or junction is formed.
■ There is a potential (difference) in the voltages between the materials
in this junction called the barrier potential.
■ In common silicon diodes, this amounts to about 0.7 Volts.
■ When a diode conducts there will be a 0.7 Volt drop across it, and
less voltage will be available for the equipment.
Diodes come in current handling ranges of milliamps (.001), to 1,000’s of Amps.
High current diodes are used in alternators to rectify AC to DC to recharge the
battery.
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THE BASIC INSTALLER STUDY GUIDE
✍ When a diode conducts
there will be a 0.7 Volt
drop across it, and less
voltage will be available
for the equipment.
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Margin Notes
Unlike resistors, diodes do not have color bands that indicate their ratings.
■ The type of diode and its application are noted in the manufacturer directories.
■ The part number is printed on the diode, and the band at one end
of the diode denotes the cathode (negative) end of the diode.
Here’s a question you will likely come across when working with diodes:
■ In the following diagram, is the diode positioned correctly so that the light
bulb will turn on when the switch is closed?
+
■
-
v
Figure 49. Diode diagram.
The answer is yes, the diode is positioned correctly and the light will turn on.
Light Emitting Diodes (LED’s) are a very special type of diode.
■ They are extremely useful as indicators (i.e., power on, function on/off, etc.).
■ LED’s are most often found in red, yellow and green, and are also
available in blue.
■ In order to avoid self-destruction, a resistor is wired in series with
one leg of the LED to limit the current through it.
✍ When an LED is forward
biased, a voltage drop of
about two volts is typical.
74
When an LED is forward biased, a voltage drop of about two volts is typical.
■ LED’s illuminate with currents of approximately 10 Milliamps and have a
life of 100,000 hours or more.
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Section 7
Automotive, Electrical and Charging Systems
Margin Notes
In Section 1, we introduced the differences between alternating current and direct
current.
Many people assume that today’s vehicles only use DC because car batteries are
DC devices.
■ The main function of the alternator is to recharge the battery and act as
the primary source of electrical power while the vehicle is being driven.
■ In this section we learn that the alternator generates an alternating current
internally…and outputs DC.
AC is turned into DC by what is known as a rectifier bridge, which is typically
built right into the alternator. A rectifier bridge is made up of diodes. At least one
pair of diodes is necessary for each “phase” of AC. Alternators produce 3 phase AC
so rectification to DC requires 6 diodes. Even a basic rectifier bridge in OEM alternators use a minimum of 6 diodes. Higher output and larger capacity alternators
that use more than 6 diodes usually do so in groups of 6, such as 12 or 18 diodes.
✍ AC is turned into DC
by what is known as a
rectifier bridge.
There is a very important fact to be aware of when designing an audio system
using multiple amplifiers and high amounts of power, especially with modern
vehicles and sensitive electronic computer controlled subsystems:
WHEN THE AMPERAGE DRAW OF A SYSTEM EXCEEDS 120% OF
THE ALTERNATOR’S MAXIMUM OUTPUT, THE CHARGING SYSTEM (both the battery and alternator) WILL BEGIN TO SUSTAIN DAMAGE, particularly to the alternator’s diodes.
■
High output, high performance alternators generally use more diodes
than standard alternators or higher current rated diodes (or both) and are
able to handle higher capacity workloads of output.
■
✍ WHEN THE AMPERAGE
DRAW OF A SYSTEM
EXCEEDS 120% OF THE
ALTERNATOR’S MAXIMUM
OUTPUT, THE CHARGING
SYSTEM (both the battery and
alternator) WILL BEGIN TO
SUSTAIN DAMAGE, particular-
It is always a great approach to advise the customer before any work
begins that an upgraded alternator and battery may be necessary to provide
reliable system performance for the audio system and power requirements
in question.
■
ly to the alternator’s diodes.
Many newer vehicles have computer controlled voltage reference inputs
which take voltage data off of the alternator and battery at freeway speeds
and in top gear to “tweak” the output so that the car can maximize fuel economy. Many Honda and Acura vehicles operate this way.
■
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Margin Notes
IGNITION SWITCH FUNCTIONS/POWER WIRING
The power wiring of most vehicles falls into four categories:
1 Battery.
2 Ignition.
3 Accessory.
4 Start.
Battery - wire that comes directly from the battery.
■ Its first stop, after the starter, is usually the “Batt” terminal on the keyswitch.
■ This wire is electrically “hot” at all times, regardless of key position.
■ This lead is often unfused.
Ignition - the position just before start, and start.
■ This lead has power to it when the engine is being cranked and also in the
“run” position, which is the position the switch falls back to after vehicle has
been started.
■ This is a vital wire to find when installing a security system.
■ This lead is often unfused.
Accessory - usually a counterclockwise turn from the “off” position, and the “run”
position.
■ It will usually power most accessories, such as radios, wipers, etc., but is
wired separately from the ignition circuits.
■ This lead is often unfused.
Start - used to start the engine.
■ This wire has a voltage on it only when the engine is being cranked.
■ Releasing the key from the start position puts the key into the ignition, or
“run” position.
■ In the start position, ignition voltage is maintained, but all accessories are
cut off because all battery power is routed to the starter.
■ This lead may be unfused.
■
Figure 50. Ignition switch diagram.
All of these wires can usually be found at the key switch and should be functionally verified with a DMM, not an incandescent type test light, so as not to damage any computers in the electrical system.
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Margin Notes
Section 8
Troubleshooting Guide
OVERALL
If there is no power in the entire system:
■ Check the main fuse at the battery.
■ To avoid a short circuit and severe damage to the vehicle - always fuse a power
cable at the battery within six inches of the battery.
If there is no power to the amplifier or amplifiers, but other components have power:
■ Check the fuses for the amplifiers first.
■ Then, check the main fuse.
If there is no power to the headunit, but other components have power:
■ Check the factory fuses (at the OEM fuse panel) labled RADIO first.
■ Then, check the main fuse at the headunit in the dash.
If an amplifier overheats, “motorboats” or fails:
■ Use Ohm’s Law ( E = I x R ) to determine if:
■ The gauge wire is too small.
■ The vehicle requires a higher output alternator.
■ The ground wire gauge is too small.
■ Use a DMM or a VOM to determine if:
■ A speaker may be “shorted out”.
■ The voltage to the amplifier is too low.
■ A fuse has blown.
If a resistor fails:
■ Use a Volt Ohm Meter (VOM) to measure current and voltage, then use
Ohm’s Law to calculate resistance.
■ Make sure you’re using the correct resistor (too low a value and it will
overheat and fail).
■ When resistors are connected in series, the total resistance is the sum
of the resistance of each component.
■ When devices are wired in parallel, the total resistance is always less
than the resistance of the component with the smallest value.
If there is a voltage drop in the system:
■ Is the voltage drop caused by a bad connection?
■ Is the wire gauge too small?
■ Look for the source of added resistance.
■ Use Kirchoff’s Voltage Law (KVL)to determine the voltage drop.
■ Remember to use effective resistance - the “calculated” resistance that
a device presents to a circuit while it is operating.
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Margin Notes
Is there “alternator whine”?:
■ Check for a ground loop.
■ Poor crimps can cause a ground loop.
■ Check the alternator.
■ Check for audio cables which run near high current power wiring.
■ Check for passive crossovers installed near factory wiring harnesses.
■ Measure the ground point potential back to the negative battery post and
with each other.
■ Single point grounding is preferred.
If the input signal voltage is too high to an amplifier:
■ Add a voltage divider (resistor network) to the signal cable.
If there are “burn marks” on the areas surrounding a resistor:
■ Make sure the resistor is not overheating.
■ Be sure there is adequate airflow around all resistors.
If the alternator fails:
■ It may be possible that the amperage draw of the system exceeds 120% of
the alternator’s maximum output. Most OEM charging systems (BOTH battery and alternator) will begin to sustain damage at that level, particularly to
the alternator’s diodes.
■ If this is the case, advise the customer before any work begins that
an upgraded alternator and battery may be necessary to provide reliable system performance for the audio system and power requirements
in question.
SPEAKERS
If tweeters are always “blowing”:
■ Install a fuse - wired in series - with the speaker.
■ To determine the proper amperage of the fuse, you’ll need to know
the ohm load of the speaker as well as its continuous or nominal power
rating.
■ Check that the output is not clipping, if it is reduce volume or gain.
■ This is often a symptom of electrical (heat related) tweeter failures.
If speakers are always “blowing”:
■ Check that the output is not clipping, if it is reduce volume or gain.
■ This is often a symptom of electrical (heat related)speaker failures.
■ Check that the excursion limit of the speaker is not being exceeded at
high volume.
■ This is often a symptom of mechanical (excursion related)speaker failures.
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If sound quality is poor:
■ Check for a bad connection or poorly crimped terminal.
■ Check that the speakers are connected in parallel.
■ When “paralleled” speakers are connected to the amplifier, the combined speaker load will have a significant effect on how that amplifier
performs. It may also cause the amplifier to run excessively hot.
■ Check to see if the LOUDNESS is switched on, if so switch to OFF.
■ Check to see if the Bass and Treble settings are boosted, if so set to FLAT.
Margin Notes
If too much power is reaching a speaker:
■ Add a power resistor to reduce the amount of power.
■ Check that the output is not clipping, if it is reduce volume or gain.
If high frequencies are reaching the subwoofer:
■ Install an inductor - wired in series - to block the higher frequency signals
while allowing the low frequency audio signal to power the speaker (this
creates a low-pass passive crossover).
If low frequencies are reaching the tweeters:
■ Install a capacitor - wired in series - to block the lower frequency signals
while allowing the high frequency audio signal to power the speaker (this
creates a high-pass passive crossover).
This concludes our discussion of 12-Volt electrical. If you’ve read each section of
this Chapter thoroughly and followed the instructions stated in the Introduction,
then you should be well prepared to answer the electrical section test questions
on the MECP Basic Installer exam.
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Margin Notes
SAMPLE TEST QUESTIONS
1
What are the four different electronic properties you will encounter?
A Amps, volts, ohms and joules
B Power, voltage, direct current, alternating current
C Resistance, voltage, ohms, inductance
D Voltage, current, resistance, power
E None of the above answers are correct
2
What is voltage?
A The rate of electron flow through a given point
B The electrical pressure that moves charged particles in a circuit
C The conductivity that various materials possess
D The relationship between current, resistance and power
E The conversion of energy into work over a certain period of time
3
Which of the following cannot be determined by Ohm’s Law?
A If a certain gauge wire is too small
B If the voltage supplied to an amplifier is too low
C If the system requires a more powerful amplifier
D If a higher output alternator is needed
E All of the above answers are correct
4 Using a VOM (Volt Ohm Meter), you can measure current and voltage, but
you cannot directly measure resistance in a live circuit.
A True
B False
5
80
A “watt” represents the conversion of one joule per second into...
A Light
B Heat
C Sound
D Some other form of work
E All of the above answers are correct
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6 What is the impact of Kirchoff’s Voltage Law if there is a poorly crimped terminal in the installation?
A There is no impact
B One volt dropped through a connector will reduce voltage to the
equipment by one volt
C One volt dropped through a connector will reduce voltage to the
equipment by two volts (1:2 ratio)
D One volt dropped through a connector will reduce voltage to the
equipment by three volts (1:3 ratio)
E There is an impact, but it is too low to measure
7
Margin Notes
Which of the following is a characteristic of a resistor?
A Resists the flow of electrons
B Can be added to a signal cable to reduce the input signal voltage to
an amplifier
C Can reduce the amount of power to a speaker
D Converts electrical energy to heat
E All of the above answers are correct
8 Electrolytic is known for its excellent sound quality and is used for the higher
crossover frequencies.
A True
B False
9
How do you determine the total resistance of a circuit?
A Add up all of the resistances
B Multiply all of the resistances
C Add the two highest resistances and divide by the lowest resistance
D Divide the voltage into the current
E Multiply the voltage by the current
10 What does a passive crossover for a basic two-way system consist of?
A Two passive filters
B One passive filter and one active filter
C One capacitor for the tweeter and one inductor for the woofer
D One bandpass filter
E One passive filter and one relay
Answers
1 D,
2 B,
3 C,
4 A,
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BASIC AND ADVANCED ELECTRICAL
5 E,
6 B,
7 E,
8 B,
9 A,
10 C
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CHAPTER 2
INSTALLATION KNOWLEDGE & TECHNIQUE
The bottom line: Working as a Professional Installer, you have to be able to
tackle the challenges that you face in your day-to-day duties. While that often
requires a high degree of creativity, it also necessitates a solid foundation in
the basics. This chapter focuses on some basic installation practices, including proper tool use and safety. These are best practices that every professional installer should follow.
Both the Basic Installer level and the First Class level Installation Knowledge
& Technique section of the MECP certification tests are included here. You
should have a thorough understanding of each topic before moving on to the
next topic. For the First Class level test read all of this Chapter as well as the
complete First Class Study Guide available from MECP.
2
INSTALLATION KNOWLEDGE & TECHNIQUE
Margin Notes
Section 1
Basic Installation Practices
A professional installation is not just about the quality of your work – it also
includes your preparedness and professionalism. A true professional understands
every aspect of the job – from the minute the vehicle arrives, until the job is done.
That means caring for your customer’s vehicle – before, during and after the installation – and properly logging anything unique that occurred during the process.
VEHICLE CHECK IN
How many times has this happened to you? You finish an installation, the customer comes to pickup their vehicle…and they accuse you of denting a fender, or
soiling their interior!
It happens – and if it hasn’t happened to you yet…it will.
But you can be prepared for the inevitable.
Here are some steps you can take to guard against this type of liability:
Perform a thorough “vehicle check-out” when it comes into the shop:
■ Before you begin any installation work, thoroughly inspect the customer’s
vehicle.
■ Start with the exterior.
■ Inspect the trunk.
■ Inspect under the hood.
■ Inspect the interior.
■
Note any damage on the repair order.
■ Make note of any flaws in the paint, body work, scratches, tears or burns
in the upholstery – anything that you could easily be blamed for later.
■
Perform a complete function check of the vehicle.
■ Use your installation worksheet to document accessories that are not in
working order. (See the Installer Check-out Sheet at the end of this chapter.)
Review your findings with the customer before they leave (and before you
start).
■ If that’s not possible, any problem – no matter how minor – should
be brought to the attention of your shop manager.
■
Note: If you develop an acute eye when examining the body and finish of a vehicle, you
may notice dings or scratches the customer never noticed before. That way, even if the
customer doesn’t remember that the door was scratched, they cannot blame you for
scratching it.
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Establish a Personal “Dress Code.” After you’ve inspected the vehicle, give
yourself a “once-over:”
■ Be sure there are no tools in your back pockets that could gouge or rip the
interior.
Margin Notes
If you wear jeans with brass rivets (and most have them), you should wear
a jump suit or smock to prevent interior/fabrics and outside paint from
being scratched.
■
■ It’s always a good idea to cover the interior with a drop cloth or blanket,
and make sure your hands and clothes are free of grease and oil that could
stain the interior.
■ When the installation is finished, a second inspection should be performed, starting with the function check and working back through the interior and then to the exterior.
These precautions take only a few minutes, but can save you and the shop owner
from being blamed for damage that existed before the car came into the shop.
Reducing unnecessary damage claims will help lower insurance costs and protect
your reputation as a reliable, “topnotch” installer.
BOOKKEEPING
At most shops, when the work is done, the job is closed, invoices are filed and that’s
it. But what happens if the customer comes back a year later with a question?
Without accurate records, you have to “start from scratch” when determining
something that could take just a couple of minutes if that information was recorded on the invoice or repair order.
When the installation is complete, log the following information on the paperwork:
■ Wire codes for installing alarms.
■ Wire colors for hooking up power supply leads and power antennas.
■ Enclosure sizes for subwoofers in specific automobiles.
■ Templates that are made for special head units, antenna, and speaker
installations.
Taking a couple minutes at the end of an installation can save you hours of time
if records are kept in well-labeled files.
In addition to installation information, information on raw-materials sourcing,
product sourcing, and people to contact in case of installation problems should
be maintained in filing cabinets as well.
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Margin Notes
VEHICLE DISASSEMBLY AND REASSEMBLY
It takes a lot of skill and patience to disassemble a dash or door panel and then
put it back together with precision.
The potential for damage during this phase of the job is enormous – and that’s
why you have to follow special precautions to ensure the job is done right.
■
First and foremost – use the proper tool.
■ Always use the appropriate tools to disassemble and reassemble a
vehicle.
■ A large, flat blade screwdriver to pry off door panels is not considered a proper tool.
■ Many tool companies (such as Snap-on, Mac, Klein, etc.) have a tool
specifically designed for removing door panels; it’s called a “panel popper”
or door clip remover.
■ This tool and many other tools from the paint and body profession
apply directly to installations.
A pair of pliers is not the correct tool to loosen the nut on a battery terminal, or a fender-mount antenna – an open-end wrench
or an adjustable crescent wrench is the better choice. (See Section
5 of this chapter for a list and description of tools.)
✍ A pair of pliers is not the
correct tool to loosen the
nut on a battery terminal,
or a fender-mount antenna.
When disassembling a vehicle, place each part in a labeled box or plastic
bin. A magnetic bowl works well for holding metal screws and clips.
■ Never leave pieces on the floor of the shop – they will only get lost,
stepped on, or broken.
■ Mark your container Left Front Door, Dash, or Rear Deck.
■ As these vehicle sections are taken apart, have the container nearby
and place each part into it as it comes off the vehicle.
■
This practice will save you a lot of stress in the long run and make the job go
much faster, especially during reassembly.
■ Another simple practice is to use a 6’ x 6’ square of carpet under each door
and sill of the vehicle.
■ If a part happens to drop off the door or fall out of your hands, it will
stop in the carpet and not bounce across the shop.
■ It will also save wear and tear on your knees.
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CABLE ROUTING/LEAD DRESS
Margin Notes
In Chapter 1, we emphasized the importance of good wiring habits. Proper installation of power lines, interconnect cords, and speaker cables can mean the difference between a job that lasts six months, or a job that lasts 10 years.
Although this phase of installation can be tedious and time-consuming, following
common sense guidelines can make it go faster, last longer, and give your install
a professional appearance.
Here are some simple guidelines to follow:
1 Always run power and signal leads away from each other.
■ The general rule of thumb is to run the battery power, remote
turn-on lead, and ground from the head unit, equalizer, or other
front-end component, down the same side of the car that the battery is on. This way most of the time you avoid having to cross the
battery lead over other vehicle wiring, which can lead to inductive coupled or radiated noise.
✍ Always run power and
signal leads away from
each other.
2 All wiring should be run away from the car’s factory wiring due to the
fact that these high-current wires can induce noise into the system.
3
Never run wiring through holes that have rough metal edges.
■ It’s easy for wiring to get pinched beneath seat tracks, clutch and
brake pedals, etc.
■ Use grommets whenever wires pass through metal boundaries.
4 When choosing sources for power supply lines for equalizers, head
units, and amplifiers, make certain that the power sources are noise-free
and have enough current-carrying capacity for the unit each wire will be
powering.
5 Terminating wiring should always be soldered, and then heat shrink
tubing should be applied to cover the complete joint.
■ While each car is different, one thing they all share is a high
vibration environment, which should always be considered when
you’re wiring.
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✍ Terminating wiring should
always be soldered then
heat-shrink tubing should
be applied to cover the
complete joint.
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Margin Notes
6 Pre-plan your wire routing and run the speaker wires and line--level
signal leads on the opposite side of the vehicle.
■ If this can’t be done, try to keep power and signal cables as far
apart from each other as possible, or a minimum of 18 inches.
■ If crossing power leads and signal leads can not be avoided,
cross them at a 90º degrees or no less then a 45º degree angle. A
90º degree angle would be the optimum.
■ The speaker and shielded leads can pick up radiated noise from
the battery power cable and induce that noise into the system.
Routing wiring this way helps avoid alternator whine (i.e., the
“siren-like” whining that appears when the rpm’s of the engine
increase).
■
POWER ACCESSING
Power is not power when it comes to most installations. You have to carefully
choose your source – and that can have a major impact on the functionality of
your installation.
Alarm installations, in particular, require that you access an assortment of power
wires:
■ Remote-controlled alarm systems need a constant +12VDC lead, a
switched ignition lead that stays live while the starter is being cranked, and
the starter wire itself.
■ Usually the best and safest place to find all of these wires is at the
ignition switch, though it is always recommended to go directly to the
battery for your +12VDC connection.
Here are some guidelines:
1
Remove the lower panel covering the bottom of the switch.
2 After unclipping and unwrapping some wires, access to the switch
can be made.
■ On autosound systems that require constant power, never
access power from the fuse block – always go directly to the battery, with appropriate fusing.
■ The fuse block is typically the noisiest spot on the vehicle to
access power.
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GROUND LOOPS/GROUND PATHS
Margin Notes
Ground loops are probably the most frequent cause of noise problems in car audio.
The procedures for eliminating ground loops can be difficult if you do not understand the theory behind what causes them.
Ground loops result when all the components in an audio system do not see
exactly the same ground. Differences in degrees of being grounded are called
ground potential.
■ The difference in potential between all the grounds of a system is what
causes a “loop,” or voltage drop, resulting in alternator whine.
✍ Differences in degrees of
being grounded are called
ground potential.
Wiring a vehicle properly and making absolutely sure that all components
are grounded at the same spot or potential is essential.
■
Points where grounds can run into a “loop” situation include:
1 The low-level leads going from the output of a head unit to the input
of a crossover or amp. (Nothing will allow noise to radiate into a system
faster than inferior cable with poor shielding. Always use high quality
cables.)
2 An amplifier or any other component mounted directly to the metal
of the vehicle.
■ Never mount components to bare metal. Always try to use an
amp rack and insulate the other components from the chassis of
the vehicle.
3 Grounding several components to chassis ground through their
ground lines.
■ Some preamp units get their B- connection directly from the
interconnect cable – connecting the black wire to ground in this
case causes an automatic ground loop.
■ Ground your preamp components to one point – usually the
back of the radio – if their power supply ground is separate from
signal ground.
4
The antenna input.
■ The use of antenna ground-breakers that are available on the market today is not a recommended practice, unless there is a severe
grounding problem with a particular vehicle.
■ This ground is essential to the reception of AM.
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Margin Notes
■
Figure 51. Ground loop.
Although there are ground-loop adapters available on the market, they are really a
“Band-Aid” approach for a system that should have been wired correctly in the
first place.
The simplest way to avoid accessory noise problems is to never share a ground
connection with the vehicle's accessory ground path, such as a fan motor or brake
light ground. It is highly likely that a pop or a buzz will be heard in the system
whenever the fan is turned on or the brakes are applied.
FINDING A GOOD GROUND
Finding a good ground can be tricky.
■ The best ground point in a vehicle is a place with a good physical connection to the same metal that the vehicle battery ground itself shares. Make
sure that it has the same ground potential as the battery ground, however it
doesn’t necessarily have to physically connect to the battery ground point.
Think of the chassis and body metal of the vehicle as one extremely large
gauge wire connecting the ground of the battery to other vehicle accessories.
■ Avoid choosing ground points that are secondary body or chassis components that may have the added resistance of tack welds or bolts between the
main and secondary parts. A hood, trunk lid, or rear deck are primary examples of secondary body components.
Avoid choosing ground points that share connections with other vehicle
accessories. This helps avoid potential noise problems from the start.
■ Be sure to scrape away the paint around the area you have chosen as
your ground point and use a star washer to make a good electrical connection.
■
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Star washers are better than flat washers for grounding because:
1 Flat washers can trap contaminates between themselves and the
grounding surface, which increases contact resistance.
Margin Notes
2 Star washers tend to bite into the grounding surface thus cleaning it
and getting more surface area for lower contact resistance.
■
Always avoid using the factory headunit power and ground wiring.
■ This wiring usually has inferior gauge and often does not go directly to ground, but picks up grounds of other vehicle systems which are
clustered together at one point.
■ Although many standard installation procedures of headunits call for
a “factory harness adapter,” systems with signal processors, multiple
amplifiers, and/or significant amounts of headunit power may be more
prone to noise related problems by using factory headunit power
wiring.
■ This can introduce clicks and pops in an audio system when other
vehicle systems switch on and off.
■ Factory wiring also runs in harnesses past other devices in the vehicle, which can radiate or couple noise into an audio system.
PROPER WIRE GAUGES
The purpose of a wire is to conduct electric current from one location to another.
Poor system wiring can induce noise and cause overall poor performance.
■ The size of the power and ground cables (Kirchoffs’ current law) used to
supply battery power to an amplifier are of utmost concern.
■ Using too small a gauge cable to power an amp will limit the amount
of current which an amp gets, thus limiting its performance.
■ An inadequate wire size could melt the insulation off the cable and
could cause serious damage to your customer's vehicle.
■ A large gauge, multi-stranded wire – with either a fuse or circuit breaker within 10 inches of the battery – is mandatory.
■ American Wire Gauge (AWG) labeling of cable is somewhat confusing – the lower the number, the bigger the cable. For example, a #12
wire is larger and will handle more current than a #16. A #22 gauge
wire is much smaller than #14.
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Margin Notes
The chart below shows the relationship between the AWG and the diameter of the
wire in inches.
AMERICAN WIRE GAUGE
Current Capacity of Wire From 0 to 20 AWG
AWG
0
1
2
3
4
5
6
7
8
9
10
12
14
16
18
20
Current Capacity
(Amps @ 680F)
150.90
119.60
94.80
75.20
59.60
47.30
37.50
29.70
23.60
18.70
14.80
9.33
5.87
3.69
2.31
1.46
PROPER CONNECTIONS
Terminating the end of a wire should be done as carefully as possible.
■ Most connections today are done with a crimp tool, which attaches the
wire to a solderless crimp-on connector.
■ When using a crimp-tool, the seam of the metal barrel, unless it is
seamless, should be in the concave part of the crimper's jaws. This
makes for a secure mechanical connection.
■ For connections in the engine compartment (under the hood) of a vehicle, it’s important to solder the connection and then heat shrink the connection and terminal with a piece of shrink tubing.
■ The tubing must cover the bottom of the connector (where the wire
enters to connector), as well as go all the way to the top of the connector.
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Cover as much of the connector as possible making a good weather
resistant seal.
■
Margin Notes
When the connection is firmly attached to the firewall, it is good practice
to apply noncorrosive grease to the screw head.
■ This helps reduce possible corrosion of the screw head and the terminal.
■
The only drawback to crimping is that over a period of time, oxidation can build
up between the wire and the connectors. This oxidation causes a degradation in
the electrical connection. In other words, it causes an increase in resistance, which
will hurt the overall performance of the unit involved.
Soldering is another alternative:
■ Solder should be applied so that it flows over the connection.
■ For best results, the iron should be held below the wire while applying the
solder from above.
■ This allows the solder to flow from the top of the wire to the bottom
more uniformly.
■ Remember to heat the connector, not the wire.
■ Two or three “balls” of solder (a cold solder joint) is not good enough
because they will contain air bubbles and either break off or have little
to no electrical connection value.
■ A good solder joint should be smooth, shiny, and concave. It is
important to remember that solder does not go from the liquid state
directly to the solid state, but has a plastic state in between. During the
plastic state, a cold solder joint can occur if the joint is moved.
✍ A good solder joint
should be smooth, shiny,
and concave.
Avoid using wire nuts. Wire nuts were designed for a stationary, stable environment – like inside a house – not many houses are designed to accelerate, decelerate, or corner.
■ The wire nut will eventually fall off the wire leaving the exposed wiring to
short to ground or to a component.
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Margin Notes
ANTENNAS
Most automobiles use one of six types of antennas:
1 Fixed mast
2 Power
3 Collapsible mast (full length)
4 Short collapsible mast (amplified)
5 Windshield
6 Diversity
Depending on the car, these antennas can be mounted through the top surface of
fenders, on the sides of fenders, through the windshield A-pillar, on the surface of
A--pillars, in the windshields, and along the back edges of the roof.
Antenna installation varies from car to car; however, proper mounting is crucial:
■ When you’re selecting the right mounting location, refer to the guidelines
supplied by the manufacturer.
■ Mounting the antenna as far away from the engine as possible will
usually reduce Radio Frequency Interference (RFI).
■ If the cable under the fender is in poor shape or is corroded, the ground
braid’s integrity can be compromised.
■ This will not allow the cable to reject radiated noise and will show
up graphically on your AM band.
■ If the rockers under the fender are not firmly digging into metal, noise can
be generated.
■ When replacing an antenna, always remove any dirt which may have
accumulated where the rockers will come in contact.
✍ Most FM antennas
are 31” long.
Most antennas (unless they’re electronically amplified) are approximately 31” long.
This is said to be the best length for FM reception (1/2 of a quarter wavelength).
Guidelines for mounting an antenna:
1 Check under the fender (front or back) for proper clearance.
2 Mark your spot with a center punch or awl.
3 Drill a pilot hole with a 1/8” bit.
4 Then use a proper size hole saw at low-to-medium speed.
5 Scrape away accumulated dirt under the fender to get the best ground possible.
6 Apply a rustproof touch-up paint to the bare metal after drilling to
insure a rust free future in your installation.
Some vehicle manufactures are equipping their vehicles with power amplified
antennas. These antennas increase performance; however, they have power leads
which must be connected to a source of power that is live when the radio is
turned on. This requires a connection to the headunit’s power antenna output
(some headunits share this output with the remote amplifier turn-on).
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FUSING AND CIRCUIT BREAKERS
Margin Notes
Installing a fuse or circuit breaker at the battery is extremely important.
■ The purpose of fusing is not to protect the component, but to protect the
wire.
■ The wire has to pass through the firewall, run under the door sills,
under the rear seat, and up into the trunk. The potential danger here
is the sill molding screws or rear seat framing/springs puncturing the
insulation of the power cable and shorting it to ground.
■ In some vehicles this is not possible because they use an under-theseat or in-trunk battery. An Audi, or BMW would be good example of
this type of configuration.
✍ The purpose of fusing
is to protect the wire.
There are a variety of different fuses. Figure 52 shows three popular types of fuses
for automotive use.
■
Figure 52. AGC, AGU and ATC fuses.
Always install a fuse in a weatherproof, rubber-type holder or a circuit breaker of
proper amperage, as close to the battery as possible but no more than 10 inches
from the positive battery post.
What is the “proper amperage” for the fuse or circuit breaker?
■ The correct fuse or breaker must exceed total amp draw, and be able to
handle the total amperage.
■ Do not use self-resetting circuit breakers. These types of circuit breakers are undesirable due to the fact that they can reset themselves until
the contacts permanently fuse. (See Chapter 1 for more information on
fuses and circuit breakers).
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Margin Notes
Section 2
Noise Troubleshooting
SYSTEM NOISE
Unintended noise entering a system can be an installer’s worst headache.
Common sense and logical troubleshooting techniques, however, will help you
through some of the most difficult problems.
✍ The first three steps
involved in troubleshooting
noise are to: Identify,
Isolate, and Eliminate.
The first three steps involved in troubleshooting noise are to:
1 Identify
2 Isolate
3 Eliminate
Identify
You can identify the noise problem by making careful observations as to what
kind of problem is occurring. Ask yourself some simple questions:
1 What are the symptoms?
2 What kind of noise is it?
3 Does the noise run through the whole system?
4 Does the noise go up and down with the volume control?
5 When did the noise start?
6 Does the noise rise and fall with engine speeds?
7 How long has it existed?
8 Is the noise affected by driving over bumps or dips?
Isolate
Once you’ve identified the problem, the next step is to isolate it to determine in
what stage of the circuit the problem exists. A thorough investigation during the
identification process will help you out at this point.
A component failure is pretty easy to trace. A quick check of its operation and/or
replacement of the component will tell you if it is indeed the problem.
✍ A word of caution is in
order here. Do not make a
habit of substituting parts
during this stage. If the
problem is a short circuit or
a reverse polarity condition,
Note: A word of caution is in order here – do not make a habit of substituting parts during this stage. If the problem is a short circuit or a reverse polarity condition, it may cost
you another part. Always check the electrical and mechanical environment around the
component in question first, then substitute.
Disconnecting and/or bypassing a component or section of the circuitry may also
be necessary to isolate the problem.
it may cost you another part.
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Eliminate
Once the problem has been identified and isolated, elimination will usually
involve one or more of three variables:
Margin Notes
1 Mechanical – involves changing the locations of components and/or
mechanical connections, for proximity-related problems.
■ Mechanical alterations usually involve radiated noise and
Electromagnetic Interference (EMI) noise as well as other problems caused by the automotive environment.
2
Acoustical – involves phase, diffusion, interference, or loading problems.
■ This type of problem may include mechanical problems as well
as require active or passive trimming of the system. (The First
Class Study Guide section on Autosound will cover troubleshooting acoustical systems).
3 Electrical – deals with filtering, positive and negative DC paths, AC
signal paths, grounding, and all of the variables of the automotive electrical system.
■ Troubleshooting electrical systems can be a very complicated
process. It requires a basic knowledge of different types of test
equipment such as an oscilloscope, LC bridge, signal generator,
and distortion analyzer. A simple hand-held AM/FM radio is an
excellent piece of test equipment when troubleshooting Radio
Frequency (RF) problems. The most basic tool, however, when
you’re troubleshooting an electrical system, is a solid understanding of the electrical components involved (see Chapter 1).
TYPES OF NOISE PROBLEMS
System noise comes in many forms:
■ Alternator whine is a whistling noise that responds in direct correlation
to the RPM’s of the engine, and is usually the result of a voltage differential
created by more than one ground path or a poor ground path.
■ The best way to test for alternator whine is with the audio system on
and the volume turned all the way down. Then “rev” the engine. If the
whine is heard, unplug the line inputs at the amp or crossover. If the
whine goes away, you've more than likely got a ground loop.
■ Make sure all your grounds are assembled at one point only and that
amp mounting, crossover mounting, equalizer mounting, etc., are not
allowing these components to touch ground.
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✍ Alternator whine is a
whistling noise that responds
in direct correlation to the
RPM’s of the engine, and is
usually the result of a voltage
differential created by more
than one ground path or a
poor ground path.
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Margin Notes
✍ Cables that are too close
together, or too close to
stock wire looms, can pick
up what is known as induced
or coupled noise.
■ Cables that are too close together, or too close to stock wire looms, can
pick up what is known as induced or coupled noise.
■ Proper wiring technique is essential – power and signal cables must
not be run together and should be separated by at least 18 inches.
■ If you have to route power and signal cables over one another, it's
best that they cross at a 90 degree angle. This practice will reduce or
eliminate induced noise.
You may have a component mismatch. The home audio industry has component values that are standardized. The autosound industry, however, does
not share this standard.
■ Adjust the crossover, equalizer, and amplifier input levels (full gain
is not a necessity) to get the components to “mate” with each other.
■ Line isolators may be necessary.
■
If the noise persists when the line-level plugs are removed from the amp, then the
noise is probably coming in on the power line (though you could have a ground
loop between the amp and a bad chassis ground point, or faulty product). Try
moving the location of the power cable away from such items as vehicle computers and stock wire looms. If this does not help, a noise filter can be put on the
power line. Be advised, however, that an in-line passive noise filter will always drop
the voltage to the amplifier and may limit its performance.
✍ If you must use a noise
filter, remember that the
majority of filters are most
effective when placed at
the noise source.
98
A high amperage noise filter is a Band-Aid – not a cure – for a problem that is somewhere else in the system.
■ If you must use a noise filter, remember that the majority of filters are
most effective when placed at the noise source.
■ Try to locate a noise filter close to the amp, crossover, or other device
that needs filtering.
■
Radiated noise is the trickiest of all noise sources to eliminate.
■ Noise can be radiated from the vehicle's ignition system (ignition coil,
spark plugs, rotor) to such vehicle components as the radio antenna,
radio, and the power harnesses in the vehicle.
■ Noise can be radiated into power and signal cables by vehicle computers, fuel pumps, and key-in ignition buzzers.
■ In these cases, the only way to eliminate the noise is to bypass these
systems.
■ To find the source of the noise, use a noise sniffer.
■ Make sure you find the true source of the noise because noise can
sometimes come from a secondary radiator.
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The cure may be as simple as moving the secondary radiator away
from the primary radiator (i.e., moving a stock wire loom a few inches
from another wire loom).
■
Remember, most types of radiated noise cannot be eliminated, they can only be
rerouted or redirected.
■ Popping and clicking in an audio system is usually caused by components
in the system sharing a common ground path with a multitude of vehicle
systems or components.
■ Brake pedals, fan motors, etc., can induce noise.
■ Identify which devices are affecting the audio system, and reground the
system to a “cleaner” ground.
■ Adding a noise filter or polarized capacitor at the source of the noise
will also help.
■ A good rule of thumb – avoid the constant 12-Volt power and
ground wires from the stock radio.
■ The 12-Volt line usually comes from the fuse block, the noisiest
point on the vehicle, and the ground is usually run to a common point
with several vehicle accessories. Both are an open invitation to noise
problems.
■
Substitution is the preferred method to find out how noise is entering a system.
■ If you think a noise problem is coming in on the power cable, run a
new one OUTSIDE of the vehicle, away from possible noise-producing
vehicle items.
■ The same can be done with line-level cables. (Remember: use high
quality cables).
■ If you think the noise is coming in on the power cable, disconnect
it from the vehicle’s battery and connect a shop (bench) 12-Volt power
supply instead.
Margin Notes
✍ Remember, most types
of radiated noise cannot
be eliminated, they can only
be rerouted or redirected.
✍ Popping and clicking in
an audio system is usually
caused by components in
the system sharing a common ground path with a
multitude of vehicle
systems or components.
✍ Substitution is the
preferred method to find
out how noise is entering
a system.
Substitution can save you the trouble of tearing the vehicle apart to find noise.
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Margin Notes
Section 3
Battery Troubleshooting
Another way noise can enter a system is if the car's battery is not fully charged.
■ A low battery will not properly filter ripple from the output of the alternator.
■ Battery problems can be caused by a number of conditions:
■ Low water in the battery.
■ Loose or corroded battery cables.
■ Slipping belts.
■ Dirt on the top of the battery.
Occasionally, you’ll have a customer who doesn't drive very often, never fully
charging the battery.
As the battery voltage drops, equipment operation becomes unpredictable.
■ A failing car battery can cause an alarm to be triggered for no apparent
reason, giving the customer the impression that the alarm is defective.
✍ When measuring current
draw from the battery,
never connect an ammeter
in parallel with the battery.
✍ NOTE: Always wear
safety glasses when working
around batteries. Proper
technique is discussed in
Section 6 of this chapter.
When measuring current draw from the battery, never connect an ammeter in parallel with the battery.
■ When a meter is switched to the ammeter setting, it creates a direct short
between the test leads.
■ Connecting these across a car battery will destroy your meter and
can be extremely dangerous due to the intense heat generated in the
test leads.
NOTE: Always wear safety glasses when working around batteries. Proper technique is
discussed in Section 6 of this chapter.
Here’s how to measure current draw:
■ The circuit must be broken and the meter inserted in series.
■ Use a shunt between the circuit, then place your DMM in parallel with the
shunt. Now remove the shunt. (see figure 53 below)
■
100
Figure 53. Current measurement.
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All of the current the circuit is drawing is now passing through the leads
of your meter.
■
Margin Notes
The following only happens if you break the circuit at either the positive or negative terminal of the battery:
■ Any current drawn by any device in the car will go through your meter.
If you’re measuring 50 milliamps on the 200 milliamp scale and then
open the door, the dome light will draw a couple of amps.
■ This is a 40 fold increase in current. Imagine what will happen if you
try to start the car and attempt to pull 350 Amps through your meter.
■
Some cars have a delay-off dome light and some alarms will draw more current
when they are first powered up.
■ If your meter does not have a high amp range, this can pose a problem.
■ If this is the case, placement of a shunt across the test leads with a
wire of suitable gauge is essential.
■ After the equipment has stabilized, remove the shunt.
To measure current drawn by devices installed with a power lead to the battery,
simply remove the fuse and connect your meter there.
■ Start on the highest range your meter has and then work down to more
sensitive ranges.
To measure current draw for the entire vehicle, remove one of the cables
from the battery.
■ It doesn’t matter which cable you remove (negative or positive),
since the same amount of current flows in both leads.
■ It’s often easier to remove the negative cable so you don’t have to
work with all the accessory leads on the positive post.
■
If current drain exceeds 45 milliamps, pull the fuses out of your fuseholders at the
battery.
■ Pull the radio fuse out of the fusebox, or remove a pull-out radio.
■ Make sure you’ve pulled the correct fuse by verifying that the suspect equipment is not operating.
■ When you have found which fuse, when removed, stops the current
draw, you have isolated the piece of equipment.
Remove any stereo equipment and bench test it to make sure you have found the
problem.
■ If the current draw is in the vehicle, advise the shop manager or the customer, depending on your situation.
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Margin Notes
If the vehicle and installed system are drawing minimal current, perform a quick
inspection or test of the battery and charging system.
■ Examine the battery cables where they attach to the battery.
■ Check to see that the ground cable is not loose on the engine block, and
that the connections are tight at the starter.
■ Loose or corroded cables are enough to cause a problem.
■
Flex the alternator belt.
■ If you can deflect it more than a half inch, it’s probably too loose.
■ Loose belts can cause slippage, which keeps the alternator from
working at full efficiency.
HYDROMETER
✍ A hydrometer is the
device used to test the
chemical condition of
the battery solution.
A hydrometer is the device used to test the chemical condition of the battery solution.
■ It measures the specific gravity (density) of the electrolyte (liquid) in the
battery.
■ If you find one or more bad cells, while some read good, it's reasonable to assume that those cells are dead, but that the alternator is continuing to charge the other cells.
LOAD TESTING
Load testing is performed to find out what kind of effect the multi-amp system
you’re installing is going to have on the vehicle's battery.
A poor or weak battery may show 12 Volts on a meter but could easily fail
under the load of several high current amplifiers.
✍ A poor or weak battery
■
may show 12 Volts on a
meter but could easily fail
under the load of several
high current amplifiers.
■
102
Figure 54. Typical hookup for load test.
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If the battery is sealed (i.e., a maintenance-free battery) – meaning you cannot use
the battery hydrometer – use a load tester.
■ If the battery tests okay, you may assume that the alternator is charging.
■
Margin Notes
If the battery fails the load test, give the alternator a quick test.
■ Measure the voltage at the battery terminal – it should be close to
13.8 Volts at all RPMs greater than idle.
■ You can use your voltmeter (see Section 4), or the meter in the load
tester.
■ If the voltage does not increase when the engine is running, the alternator or voltage regulator has failed.
Section 4
Meters and Test Equipment
DMMS AND VOMS
The majority of electrical measurements you’ll make during an installation – and
a great deal of the troubleshooting – is accomplished with a meter.
The Digital Multimeter (DMM) is a multi-purpose instrument that combines the
features of an ammeter, voltmeter, and ohmmeter into one instrument. The DMM
is so versatile, it’s probably the most widely used piece of test equipment in the
electronics industry.
DMMs read out the voltage, amperage, milliamperes, or ohms being measured on a
digital readout.
■ If you exceed a range, the display will read OL (overload).
It is important to be careful when measuring current in the amp positions of a
DMM. Because the DMM is in series with the battery and the loads of the car, the
meter normally has an internal fuse to protect itself. If the fuse has been blown
by placing the DMM in the wrong setting (too low a setting when measuring high
current), you might think no current is flowing. This is DANGEROUS!
Besides the ease of use and interpretation a DMM offers, there is one undeniable
advantage in using a DMM over the standard analog meter: In today's computerequipped vehicles, the current draw that a VOM or, in particular, a standard
incandescent test light requires, can permanently damage delicate automotive
computers.
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NOTE: Never probe a vehicle’s electrical system that is heavily regulated or controlled
by computers with a VOM or an incandescent test light.
✍ Never probe a vehicle’s
A DMM will not emit the popping noise in the speaker that a VOM will.
electrical system that is
Here’s a word of advice: Keep the old VOM on the bench, and keep the DMM and
a 1.5-Volt battery with you at the vehicle.
■ The 1.5 Volt battery can be used for checking speaker polarity and continuity.
heavily regulated or controlled by computers with
a VOM or an incandescent
test light.
■
Figure 55. Example of a Digital Multimeter (DMM).
The Volt-Ohm Meter (VOM) is called an analog meter because a needle or pointer is read against a calibrated scale to measure the electrical parameter under
investigation.
■ This measurement requires visual interpretation of the data against the
meter scale, which can be a source of reading error.
The analog meter has function and range scales across its display. The functions
include:
■ AC volts
■ DC volts
■ Resistance
■ DC amps
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The voltage ranges from .25 to 1,000 Volts; the resistance (ohm) scales from R x
1 to R x 1K; a number of milliamp and amperage ranges; and possibly a dB range.
The function and range switches are combined on some meters and are accessed
through a single selector switch.
■
Margin Notes
Figure 56. Example of a Volt-Ohm Multimeter (VOM).
All meters have two leads – typically one red and one black:
■ Red is the positive lead.
■ The red lead plugs into the “+V, ohm, A” or “+” jack.
■ The red lead goes to the positive end of the measured item.
■ Black is the negative lead.
■ The black lead always plugs into the “common” or “-” jack.
■ The black lead would be attached to the negative side of the measured item.
Simply set the function switch above the type of parameter to be measured and
the range switch above the anticipated value being measured, without going
under range.
When measuring an unknown voltage or current, always select the highest range
possible and work down. (This is a good practice and should be made a habit for
meter safety).
■ If an analog meter goes off the scale, damage to the delicate needle movement could result if it is not internally protected.
To use a VOM, set the function switch to the type of energy to be measured, then
set the range switch to the amount of anticipated energy, without going under-range.
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Margin Notes
For example, if you want to find the ignition start wire of a vehicle to facilitate the
starter kill function of a security system, you would connect the meter as follows:
1 Set the range scale knob (unless the meter has auto-ranging) to the
highest voltage and proper polarity that you expect to encounter.
■ Since virtually all vehicles are negative ground and deliver direct
current, set the function knob at DC volts, and the ranging knob
to something that would include the 12V range.
2
Connect the black (negative) lead of the meter to a good chassis ground.
3 Probe the wires coming off the ignition switch with the red (positive)
lead as the starter is being cranked.
■ The wire that shows a reading on the meter – only when the key
is in the “start” position – is the wire to be relay interrupted.
4 If you want to check the amperage draw of a component or security
system brain you would proceed as follows:
■ Set the function knob to DC amps.
Use the range selector to select the highest amperage draw you
think the component could draw.
■ As a rule of thumb, check the fuse size of the component you’re
testing. If the suspect component is not blowing the fuse it comes
with, set your amperage scale on your VOM to a range just above
the fuse rating on the component and then move down to a more
accurate scale.
■
✍ Remember, amperage
draw is measured with the
meter in series with the
device being measured.
Remember, amperage draw is measured with the meter in series with the device
being measured. This means that the power wire going to the component being
measured will go to one lead of the meter, and the other lead of the meter will go
to the power source.
The analog VOM works quite well as a speaker continuity tester.
■ Set the range scale to R x 1.
■
Connect the probes across the negative and positive terminals on the speaker.
■ A clicking or popping noise – as well as a reading on the meter‘s scale
– will inform you that a speaker has continuity.
Note that when measuring ohms on an analog meter, it’s always advisable to short
the positive and negative leads together and use the “ohms adjust” or “zeroing
thumbwheel.” This will calibrate the pointer and adjust the ohms scale for greatest
accuracy. The DMM is self-zeroing.
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Most VOMs will measure voltage – both AC and DC, amperage (usually milliamps,
although some will measure up to 10 Amps on a dedicated setting), and resistance
(ohms). However, a VOM cannot be used for something it’s not designed to measure. For example, you cannot measure current (amperage) with a meter that has
every scale but an amperage scale. Likewise, you cannot measure ohms on a meter
that does not have a resistance scale. (Remember that to measure resistance, your
meter must have good batteries in it).
When using a VOM on a voltage scale, its sensitivity is expressed as the ohms per
volt rating.
The following scale shows a resistance reading from an analog meter:
Margin Notes
✍ When using a VOM on a
voltage scale, its sensitivity
is expressed as the ohms
per volt rating.
■
Figure 57. Reading from an analog meter.
At first look, you might assume the reading is 7 Ohms. However, what range was
the meter set to? If it was set to R x 1, you would be correct at saying 7 Ohms.
However, what if the range scale were set to R x 100, or R x 1 K? With an analog
meter, simply divide or multiply the reading you get by the position of the range
switch.
■ The 7 Ohm reading on the R x 100 scale would be 700 Ohms.
■ The 7 Ohm reading on the R x 1K would be 7,000 Ohms.
With an analog meter, before measuring any resistance value, be sure to zero the
pointer prior to using the meter.
■ This ensures as accurate a reading as possible.
■ If the needle on the previous scale were all the way to the left, it
would be exhibiting a condition known as INFINITY, where the resistance is so high that it is unmeasurable.
■ An INFINITY reading on a speaker voice coil usually indicates that
the voice coil has melted or opened.
■ On the other hand, if a ZERO reading appeared on the scale, there
would be so little resistance, that a voice coil with this reading would
indicate a short circuit.
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■
Figure 58. Read voltage on an analog meter.
To read voltage on an analog
meter, refer to the following drawing:
The scales are used for all AC and DC voltage, and DC amperage measurements.
■ In the preceding diagram, if the range were set on the 250-Volt scale, DC
voltage, we could read this directly at 25 Volts.
If it were set on the 25-Volt scale, this would have to be divided by 10, or
a reading of 2.5VDC.
■
With analog meters, attention must be paid to the position of the leads:
■ The red lead connects to the +, or positive input of the meter, and goes to
the same polarity on what is being tested.
The black lead connects to the -, or negative input of the meter, and goes
to the negative polarity of whatever is being tested.
■
Figure 59. Digital readout.
DMMs have no such restrictions. If you connect the
leads in the wrong direction, a minus sign appears in the display:
■
Direct current is normally a steady state voltage that does not vary over time.
■ If you encounter a problem with the charging system, the VOM has the
advantage of being able to easily read fluctuating voltage at the battery or
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alternator.
■ The VOM display can vary continuously, giving you a read-out in a
smooth continuous manner.
■ The digital scale of the DMM does not vary continuously and cannot read the full range of voltage fluctuation.
■ Some of the newer DMMs incorporate an analog scale or bar at the
bottom of the display, specifically for the purpose of reading fluctuating voltages.
Margin Notes
TEST LIGHTS
Today’s highly computerized vehicles have made incandescent test lights nearly
obsolete. The large amount of current that an incandescent test light draws can
short computer-attached logic leads to ground, destroying vehicle computers.
■ Avoiding incandescent test lights will save you time, money, and a lot of
embarrassment.
✍ Avoiding incandescent
test lights will save you
time, money, and a lot of
embarrassment.
NOISE SNIFFERS
Noise sniffers are used to “hone in” on noise-producing vehicle systems which are
radiating into an audio system. They can be purchased from a number of suppliers, or can be shop made.
■ They can easily be built from an old walkman-type cassette player.
■ A noise sniffer is basically an AM radio with a wand or probe.
■ When placed in the vicinity of a suspected noise-producing component (such as the vehicle's spark plugs, ignition coil, plug wires), it will
exhibit the same type of noise found in the system.
■ The closer the sniffer gets to a noise-producing component or system,
the louder the noise will get. This indicates what system in the vehicle
needs to be suppressed, replaced (if ignition related), or avoided.
Section 5
General Installation Tools & Equipment
The mobile electronics installation bay requires a variety of different powered and
non-powered tools. The following list should give you an idea of the range of tools
that may be necessary:
Specialty Tools:
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1
2
3
4
5
6
Door/Window crank handle spring clip removal tool
Door Panel clip removal tool
Hole saw bits 3/4”, 1”, 1 1/4”
Unibits (sometimes called step drill bit)
Special theft-resistant shaftnut removal socket
Six-Point General Motors screwdriver bit
General Equipment:
1 Crimp tool – multiple gauge
2 Drill – variable-speed, reversible
3 Drill bits – high-speed, metal 1/8” to 1/2”
4 Dremel moto-tool and accessories (for plastic alterations)
5 Electrical tape (Scotch #33+)
6 Hand or Power nibbler
7 HotKnife
8 Magnet – mechanic type or other
9 Magnetic Screw drivers – Phillips #1, 2, 3; slotted #1 and 2
10 Marking set – pencils, pens, chalk, laundry type markers (indelible)
11 Mechanics Mirror
12 Metric allen wrench set
13 Pliers – channel lock, needle nose, and standard
14 Punch – 1/8” – 1/4”
15 Putty knife – 1”
16 Right and left handed metal sheers (aviation snips)
17 Sabre saw and bits-variable speed
18 Scratch awl (scribe)
19 Single hand hack saw
20 Socket wrenches – metric, 1/4” and 3/8” drive, 5mm – l4mm sock
ets. S.A.E. 1/4” – 5/8” sockets
21 Soldering gun with rosin flux solder
22 Standard allen wrench set
23 Tape measure – metric and inch
24 Vacuum cleaner – portable, or wet-dry canister type
25 Volt-Ohm Meter (VOM)
26 Digital Multimeter (DMM)
27 Wire stripper – multi gauge
28 Wire ties
29 X-Acto knife, razor blades, utility knife
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30 X-Acto razor saw blades
31 Heat gun
Shop Equipment for Custom Fabrication:
1 Air compressor
2 Dual trace oscilloscope
3 Extension boxes for 120V AC power
4 Fabrication components (grille cloth, carpet, glue, etc.)
5 Large glue gun
6 Large current capacity battery charger
7 Portable fluorescent lighting
8 Photographic equipment
9 Realtime analyzer (Fast Fourier Transform System)
10 Signal generator (RF and AF)
11 Shop tools:
a. Drill Press
b. Grinder
c. Milling machine
d. Router
e. Sander
f. Table saw
g. Vises
12 Soldering stations
13 Ventilated booth – for painting and fiberglass fabrication
14 Welding torch
15 Work benches (carpeted for door panels, plain for wood working)
16 Computer for speaker enclosure design
NON-POWERED HAND TOOLS
In the category of non-powered hand tools, essentials include the following:
■ A full set of straight blade and Phillips tip screwdrivers.
■ #2 Phillips is the most common, even for screw guns.
■ A full set of S.A.E. and metric sockets, along with the appropriate ratchets,
extensions, “U” joints, and handles to facilitate every conceivable angle.
■ A 10mm socket is the most commonly used socket for European
and Japanese cars.
A full set of open-end wrenches, both S.A.E. and metric, as well as
adjustable wrenches.
■
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■
A good pair of diagonal cutters (commonly referred to as dikes).
■
A set of long-nose pliers, regular pliers, vice grips, and crimping tools.
A set of shaft sockets (although DIN-sized radios are rapidly replacing the
shaft radio, shaft sockets are still invaluable).
■ Shaft sockets are like regular sockets, but have longer shafts with no
internal obstacles to inhibit sliding over the shaft.
■
■
A full set of files – both rough and finish.
■
Keyhole saws, hack saws, hack saw blades, and razor knives.
■
A full set of aviation metal shears (also called tin snips).
■ Be sure to get the left cutting for counterclockwise cutting, right cutting
for clockwise cutting, and the straight cutting for straight cuts.
■
A good pair of industrial-duty shop scissors for cutting fabrics.
A full set of metric and standard allen (hex) key wrenches, as well as a full set
of torx wrenches. They are not interchangeable, so you'll need them both.
■
■
A small level to make sure speakers are straight in doors and on rear decks.
POWERED HAND TOOLS
This category usually includes the following:
Drills:
■
Cordless drills are most common.
Use drills – either cordless or cabled –which have variable speed trigger
controls.
■ This allows you to control the speed at different times in the drilling
procedure.
■
✍ If you use a drill as a
screw gun, your best
choice is a cordless drill
If you use a drill as a screw gun, your best choice is a cordless drill with
variable speed, reversing capability, and a clutch.
■
with variable speed,
reversing capability,
and a clutch.
■ One of the handiest drills is the right-angle drill, which enables you to get
into areas that a regular drill cannot.
If you’re going to be drilling a 3/8” hole through double metal, the low
torque and slow rpm of a cordless drill will take a lot more time; a 3/8” electric, high rpm drill will cut right through the metal.
■ Too high of a speed can burn up and destroy drill bits.
■
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When trying to turn large hole saws, advancing to a 1/2” drill, 1 hp or better, is usually necessary to provide the necessary torque.
■
Margin Notes
Jigsaw/Sabre Saw:
■ These saws are used for cutting metal, wood, and plastics and are available as cordless models and offer variable speed.
■
Be sure to use the proper blade for the material being cut.
■ Fine-toothed blades should be used for cutting metal and plastic;
coarse blades for wood.
■ Always take safety precautions when using this type of saw, especially
when cutting corrugated metal panels.
■
Eye protection is a must.
Hand Router and Power Saw:
■ These are required for woodworking, and should be operated by only
knowledgeable and skilled installers or woodworkers.
Soldering Iron:
■ Soldering irons can be the standard Weller 8200 soldering gun or cordless
model (Ultra torch UTS 100). Be careful though – high wattage guns can
damage PC boards and small connectors.
■ A 25-40 Watt pencil-type soldering iron and stand should be handy on
the bench.
LARGE SHOP TOOLS
This category includes:
■ A table saw, if you’re building a lot of speaker enclosures and custom panels.
■
A drill press is desirable, but not necessary.
Some shops like to use air tools instead of, or in combination with, electric hand
tools. If you’re using air tools, make sure the compressor and tank assembly are
up to the capacity of the work load asked of it.
SPECIALTY TOOLS
Dremel Moto-Tool:
■ This device is about as small as an electric razor and has every conceivable attachment.
■
A Dremel tool can be used as a small electric drill or a rotary file.
■ With a saw-blade attachment, it will easily cut through ABS plastic,
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Margin Notes
but it usually doesn’t have the power necessary to cut or grind metal.
For such jobs, use an air or electric hand held grinder.
Power/Hand Nibbler:
■ A hand nibbler takes small, rectangle-size pieces out of metal.
■ A disadvantage of the hand nibbler is that it is heavy and sometimes
awkward to use.
■ Bosch, Makita, and other manufacturers offer a power nibbler that is
much less taxing on the hands, but does leave small crescent shaped
pieces of metal which can be very dangerous and should be cleaned up
as soon as you are finished cutting.
Signal Amplifier (Head Amp):
■ This is used to boost the voltage level of a preamp signal.
■ Commonly used when the output voltage of a headunit is too low to
adequately drive an electronic crossover or amplifier.
■ It’s installed between the output of the head unit and the input of the
crossover/amp.
■ The output gain is usually adjustable.
EMR Detector:
■ This tool is used to find the source of low frequency tape head interference, or EMR, Electro-Magnetic Radiation.
Speaker-Level Adapter/Converter:
■ This device is used to convert the speaker outputs of any head unit into
line-level or preamp level leads.
■ The benefits include a much lower noise and distortion levels.
■ The preamp level can be connected to other components in the system via regular shielded leads (RCA cables).
CUTTING TECHNIQUES
Wood:
Wood can be cut with a sabre saw (jig saw), a regular crosscut saw, a keyhole saw,
or a table saw:
■ When using a sabre/jig saw, a rougher-toothed blade is preferable to a finer-toothed blade.
■ To smooth out roughly cut wood (speaker holes, for example), use
a wood file.
■
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The best way to cut speaker holes in wood is with a hole saw.
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Make sure you have an electric drill with enough torque to handle
the job, and that your hole saw blade is sharp.
■
Margin Notes
A router with a hole cutting attachment – if properly used – makes a perfect hole ready for rabbitting and speaker installation. It is also quicker than
the other methods.
■
Metal:
Metal can be cut with a hack saw, aviation shears (tin snips), or a jig/sabre saw
with an appropriate fine-toothed blade.
■ For either wood or metal, a drill – with usually a 3/8” bit – can be used
to drill a starter hole. This allows the sabre saw blade, or tin snips, to get
started.
■ Care should always be taken not to “push” a jig saw blade as it cuts. This
could cause it to heat up and burn its way through a hole instead of cutting.
The saw blade could also break, injuring the user or damaging the vehicle.
An air chisel or metal nibbler should be used by only an experienced
installer.
■
Upholstery:
Upholstery must only be cut with a razor knife or a type of razor blade.
■ A drill can damage the fabric if it is not first cut away with a knife.
■
Carpeting can wrap around a drill, creating a hazard when it unweaves.
■
Vinyl can stretch and rip apart if caught by a hot, high rpm drill bit.
Section 6
Shop Safety
You’ve probably heard the popular slogan, “Safety First.”
This is especially true for installers – particularly when you have three jobs waiting…and it’s four o’clock on Friday afternoon!
In the real world, safety often comes last.
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✍ The Occupational Safety
and Health Administration
(OSHA) is the government
agency that regulates onthe-job safety.
It’s important to stress, however, that the installation bay offers a variety of hazards. Electric shock, hazardous chemicals, and sharp tools are just a few.
The Occupational Safety and Health Administration (OSHA) is the government
agency that regulates on-the-job safety.
■ OSHA requires that all employers maintain a safe and healthy work environment.
■ The Code of Federal Regulations (CFR) lists safety and health standards,
and employers face stiff fines if these standards are not followed.
While the shop owner is ultimately responsible for accidents, safety begins with
the individual. Therefore, a properly maintained attitude is your most important
“tool” to help promote shop efficiency and safety.
SAFETY PRACTICES
✍ Always wear safety
glasses or goggles.
✍ OSHA has specific regulations for hearing protection.
Listening to a sound system
The installation bay is no place for playing games or fooling around. Protect yourself from horseplay that can lead to accidents, and always wear the appropriate
gear before you begin a job. You will only lose that right eye or index finger once,
and after the fact is too late to start being careful.
Eyes:
When using power tools – such as power nibblers, routers, jig/sabre saws, radial
arm saws, Dremel tools, etc. – Always wear safety glasses or goggles.
■ Some installers think wearing safety glasses makes them look “un-cool.”
However, looking “cool” does little good if you’re permanently blinded by
flying wood or metal chips.
Ears:
OSHA has specific regulations for hearing protection. Listening to a sound system
playing at 100 dBA SPL for
two hours will start to cause
NOISE EXPOSURE CHART
hearing damage.
Sound Level (dBA)
80
85
90
95
100
105
110
115
120
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Maximum 24-Hour Exposure
Occupational
Nonoccupational
8 hr.
4 hr.
2 hr.
1 hr.
30 min.
15 min.
0 min.
4 hr.
2 hr.
1 hr.
30 min.
15 min.
8 min.
4 min.
2 min.
0 min.
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INSTALLATION KNOWLEDGE & TECHNIQUE
playing at 100 dBA SPL for two hours will start to cause hearing damage.
■ If you’re constantly exposed to high decibel sound, wear earplugs or ear
protection.
Respiratory:
When working around sawdust or other airborne material, always wear a dust
mask. Fiberglass and particle board are especially hazardous. The glue in particle
board is toxic, and fiberglass can cause severe skin irritation and lung damage if
it is inhaled.
When working with lead based solder, it should never be heated in excess of
1000°F, at this point the solder becomes vaporized and emits hazardous vaporized lead oxide. Be sure to check the soldering iron temperature rating before soldering. Always solder in a well ventilated area.
Margin Notes
✍ When working around
sawdust or other airborne
material, always wear a
dust mask.
✍ Use gloves – full or partial
– to protect your fingers and
Hands:
Use gloves – full or partial – to protect your fingers and skin from being torn, cut,
or burned.
■ Be particularly careful when working with large power tools.
skin from being torn, cut,
or burned.
✍ Never strike a match,
a lighter, or anything that
SAFETY AROUND BATTERIES
creates a spark or flame
By their very nature, batteries present a number of hazards. Chemical reactions
taking place inside of batteries generate flammable vapors. Therefore, never strike
a match, a lighter, or anything that creates a spark or flame near a battery.
Although most modern batteries are sealed, older batteries still have vent caps
which need to be opened to be filled with distilled water.
■ While working around battery fluids, take extreme care not to come in
contact with the main chemical ingredient, sulfuric acid.
■ Sulfuric acid is highly volatile, and will burn through clothing and
skin, not to mention what can happen if it comes in contact with eyes.
near a battery.
✍ Sulfuric acid is highly
volatile, and will burn
through clothing and skin,
not to mention what can
happen if it comes in
contact with eyes.
SAFE TOOL USE
Make sure you know how to properly handle any tool – powered or not – before
you pick it up.
■ If improperly used, the air chisel is the most dangerous tool in the shop.
■ Just the noise generated by this tool is enough to damage hearing if
protection is not used.
■ If proper precautions are not taken, a window can shatter in a door
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and the rear window seal can have its integrity diminished due to the
vibrations caused by an improperly used air chisel on a rear deck.
Dikes, long nose pliers, and crimp tools should have insulated handles.
■ These are insulated not only for your comfort in reducing blisters from
crimping and cutting all day, but to insulate you from electrical shock,
should you accidentally hit a live wire or battery terminal.
FIRE EXTINGUISHERS
The laws of most states, cities, and counties require any shop which is working
on motor vehicles to have at least one fire extinguisher on the premises. Fines
and/or possible jail sentences await those who refuse to comply with this law.
✍ The extinguisher best
suited for a mobile electronics shop is the Halon type.
Most fire extinguishers work by removing the source of oxygen from the fire. The
types of extinguishers are noted as follows:
■ Type A – for wood and paper
■ Type B – for oil and flammable liquids
■ Type C – for fires of an electrical nature
■ Halon – for all types of fires
The extinguisher best suited for a mobile electronics shop is the Halon type. Always
make sure that the extinguisher is serviced at the appropriate interval, according to
the tag which was affixed to it during the last inspection or recharging.
Should you be unfortunate enough to have to fight a fire:
■ Always point the nozzle on the extinguisher toward the base of the flames
– not the burning material.
■
Only attempt to fight small, controllable fires.
■ If a fire looks as though it’s getting out of hand, always contact the
fire department.
■ Never try to fight larger fires on your own.
■ Remember, what may “look” like a fire may be only the insulation
melting off a wire, so don’t panic and reach for the fire extinguisher. The
bills to pay for cleaning a vehicle's interior can easily eat into profits.
CLEANING THE SHOP
Keeping the shop clean is also a part of safety, to say nothing about professionalism.
■ A clean shop reassures the customers that they’ve made the right choice
about your services.
Follow these guidelines:
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■
Floors should be swept up as often as possible.
Margin Notes
Reels of cable should be put back on their racks.
Boxes that equipment came in should be put in the owner’s car or properly recycled.
■
■
■ When cleaning up metal chips from power nibblers, or other tools, never
leave them on the floor to be swept up later.
■ These chips can find their way into customers’ tires, the interior of
their cars, and the bottoms of your shoes.
■ An old magnet can easily pickup stray nibbler chips to keep them
from being tracked all over the shop.
■ A heavy-duty shop vac is essential in every shop.
FIRST AID
Try as we may to operate safely, the occasional accident will happen.
■ Every phone in the shop should have the number of the nearest hospital
emergency room, police department, and fire department.
Every shop should have a first aid cabinet well stocked with bandages, adhesive
tape, antibiotic first aid cream, eye wash, iodine, and alcohol.
■ These are available at medical supply houses and industrial supply houses.
■
The cabinet should be kept at a convenient, central location.
■
It’s advisable that one or more of your crew knows basic first aid and CPR.
Finally, because installers work with a lot of rusty metal, screws, and other unsavory items, you should get a tetanus shot every seven years.
Section 7
Troubleshooting Guide
OVERALL
The customer comes to you with a physical problem (scratched paint, dirty
or torn interior, etc.) after the installation:
■ Review the “vehicle check-out” form with the client.
■ Show them where the damage was noted on the form prior to the
installation (and that the client signed that form before work was started.)
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■ If you – or someone in your shop – did the damage, take responsibility and get it repaired.
The customer returns a year after the installation with a question and/or problem:
■ Refer to the job log (which should be kept on file). It should include:
■ Wire codes for installing alarms.
■ Wire colors for hooking up power supply leads and power antennas.
■ Enclosure sizes for subwoofers in specific automobiles.
■ Templates that are made for special head units, antenna, and speaker
installations.
■ Information on raw-materials sourcing, product sourcing, and people
to contact in case of installation problems.
NOISE PROBLEMS
The three keys to noise problems:
1 Identify
2 Isolate
3 Eliminate
How to identify the problem:
1 What are the symptoms?
2 What kind of noise is it?
3 Does the noise run through the whole system?
4 Does the noise go up and down with the volume control?
5 When did the noise start?
6 Does the noise rise and fall with engine speeds?
7 How long has it existed?
8 Is the noise affected by driving over bumps or dips?
Isolate:
Once you have identified the problem, the next step is to isolate it to determine
in what stage of the circuit the problem exists.
Eliminate:
Here are some suggestions to help you eliminate various “noise” problems:
■ Check that the power and signal leads are run away from each other.
■ Is the battery lead crossing over other vehicle wiring?
■ Is your wiring next to any factory wiring harnesses?
■ Check for passive crossovers installed near factory wiring harnesses.
■
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Is the power source noise-free?
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Does the power source have enough current-carrying capacity for the unit
each wire will be powering?
■
Margin Notes
Are the speaker wires and line--level signal leads on the opposite side of
the vehicle?
■ If this can’t be done, try to keep power and signal cables as far apart
from each other as possible – or a minimum of 18 inches.
■ If you have to route power and signal cables over one another, it’s
best that they cross at a 90 degree angle.
■
■
Is power being accessed from the fuse block or directly from the battery?
■ The fuse block is typically the noisiest spot on the vehicle to access
power.
■ Check that sill molding screws or rear seat framing/springs have not
punctured the insulation of the power cable and shorted it to ground.
■ Is an amplifier or any other component mounted directly to the metal of
the vehicle?
■ Always use an amp rack and insulate the other components from the
chassis of the vehicle.
■
How are the preamps grounded?
■ Some preamp units get their B- connection directly from the interconnect cable – connecting the black wire to ground in this case causes an automatic ground loop.
■ Ground preamp components to one point – usually the back of the
radio – if their power supply ground is separate from signal ground.
■ Do any components share a ground connection with the vehicle's accessory ground path?
■ If the autosound system shares a ground with a fan motor or brake
light ground, it is likely that a pop or a buzz will be heard in the system whenever the fan is turned on or the brakes are applied.
■
Are you using the factory head unit power and ground wiring?
■ This wiring usually has inferior gauge and often does not go directly to ground, but picks up grounds of other vehicle systems which are
clustered together at one point.
■ Factory wiring typically runs in harnesses past other devices in the
vehicle, which can radiate or couple noise into an audio system.
■ Try moving the location of the power cable away from such items as
vehicle computers and stock wire looms.
■ If this does not help, a noise filter can be put on the power line (an
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Margin Notes
in-line passive noise filter will always drop the voltage to the amplifier
and may limit its performance.)
■ If you think a noise problem is coming in on the power cable, run a
new one OUTSIDE of the vehicle, away from possible noise-producing
vehicle items just to check.
■
Is it radiated noise?
■ To find the source of the noise, use a noise sniffer.
■ Make sure you find the true source of the noise because noise can
sometimes come from a secondary radiator.
■ The cure may be as simple as moving the secondary radiator away
from the primary radiator (i.e., moving a stock wire loom a few inches
from another wire loom).
■ Most types of radiated noise cannot be eliminated, they can only be
rerouted or redirected.
■
Is the antenna is the source of the noise?
■ Mounting the antenna as far away from the engine as possible will
usually reduce Radio Frequency Interference (RFI).
■ With the antenna – are the rockers under the fender firmly digging
into metal?
■
Noise can enter a system is if the battery is not fully charged
■ A low battery will not properly filter ripple from the output of the
alternator
■ Battery problems can be caused by a number of conditions; check for:
Low water in the battery
Loose or corroded battery cables
Slipping belts
Dirt on the top of the battery
One dead cell with five other good cells
If there is a problem with the wiring:
■ Are wires through holes that have rough metal edges?
■
Are grommets used whenever wires pass through metal boundaries?
■
Are wires getting pinched beneath seat tracks, clutch and brake pedals, etc.?
If there is a loose connection:
■ Are terminating wires soldered and then covered with heat shrink tubing?
■ Connections in the engine bay of a vehicle should be soldered.
■ When the connection is attached to the firewall, have you applied
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noncorrosive grease to the screw head?
■ Is the solder joint smooth, shiny, and concave? (It should be).
■
Margin Notes
If using a crimp-tool, is it a secure mechanical connection?
■ When using a crimp-tool, the seam of the metal barrel (unless it is
seamless) should be in the concave part of the crimper's jaws to ensure
a secure mechanical connection.
■ Over time, oxidation can build up between the wire and the connectors (this oxidation causes a degradation in the electrical connection, causing an increase in resistance, which hurts overall performance).
In a remote-controlled alarm system installation, you do have a constant +12VDC:
■ Is the system wired to the ignition switch?
■
Is the system wired directly to the battery?
Is there “alternator whine”:
■ Here’s how to check: With the audio system on and the volume turned all
the way down, “rev” the engine – if the whine is heard, unplug the line
inputs at the amp or crossover; if the whine goes away, you’ve more than
likely got a ground loop.
■ Make sure all grounds are assembled at one point only and that amp
mounting, crossover mounting, equalizer mounting, etc., are not allowing these components to touch ground.
■
Check for a ground loop:
■ Poor crimps can cause a ground loop.
■ Check low-level leads going from the output of a headunit to the
input of a crossover or amp.
■ Noise can be caused by using inferior cable with poor shielding.
■ Do you have a “good” ground? (Metal-to-metal contact).
■
Check the alternator.
Measure the ground point potential back to the negative battery post and
with each other.
■ Single point grounding is preferred.
■
If a fuse is always “blowing”:
■ Be sure the fuse meets the total amp draw and is able to handle the total
amperage.
Remember amplifiers that run more speakers at lower impedances use more
current.
■
■
Use a DMM or a VOM to determine if:
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A speaker may be “shorted out.”
The input voltage to the amplifier is too low.
Is there an intermittent problem with the alarm being triggered for no apparent
reason?
■ A failing car battery can cause an alarm to be triggered for no apparent
reason, giving the customer the impression that the alarm is defective.
■ Loose or corroded cables can also cause a problem.
■
■
In case of a fire:
■ Point the nozzle on the extinguisher toward the base of the flames – not
the burning material.
■
Only attempt to fight small, controllable fires.
■ If a fire looks as though it's getting out of hand, always contact the
fire department.
■ Never try to fight larger fires on your own.
■ What may “look” like a fire may be only the insulation melting off a
wire – don’t panic and reach for the fire extinguisher.
Every shop should have a first aid cabinet well stocked with bandages, adhesive tape, antibiotic first aid cream, eye wash, iodine, and alcohol.
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Margin Notes
SAMPLE TEST QUESTIONS
1 Which of the following is not part of the “vehicle check-out” that is performed
before starting work?
A Inspect the body.
B Inspect the trunk.
C Inspect the battery level.
D Inspect under the hood.
E Inspect the interior.
2 You should maintain a personal dress code to help you from being blamed
for damage that existed before the car came into the shop.
A True
B False
3
What is the general rule of thumb regarding power and signal leads?
A Always run power and signal leads next to each other.
B Depending on the installation, it’s okay to cross the battery lead.
C Run the wiring parallel to the car’s factory wiring for ease of routing.
D Run the battery power lead down the same side as the battery.
E All of the above answers are correct.
4 Ground loops are the most frequent cause of noise problems in car audio
installations.
A True
B False
5
When should you use wire nuts in an installation?
A Always.
B For the power lead.
C For speaker connections.
D Never.
6
How do you test for “alternator whine”?
A Turn the audio system on, turn volume all the way down, then
“rev” the engine.
B Turn the audio system off, then “rev” the engine.
C Use a noise sniffer.
D Use a Digital Multimeter.
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E All of the above techniques can be used to test for alternator whine.
7 Which of the following is the best diagnostic tool for use on a brand new car
with a computer-controlled ignition, computerized climate control system and a
trip computer?
A VOM (Volt-Ohm Meter).
B Test light.
C DMM (Digital MultiMeter).
D Hydrometer.
8 If you want to check the amperage draw of a component or security system
brain, and the suspect component is not blowing the fuse it comes with, you
should set your amperage scale on your VOM to a range above the fuse rating of
the component.
A True
B False
9 According to OSHA (Occupational Safety and Health Administration), what
will cause hearing damage?
A Listening to a sound system playing at 90 dBA SPL for four hours.
B Listening to a sound system playing at 95 dBA SPL for three hours.
C Listening to a sound system playing at 100 dBA SPL for two hours.
D Listening to a sound system playing at 105 dBA SPL for one hour.
E Listening to a sound system playing at 110 dBA SPL for four minutes.
10 Which type of fire extinguisher is best suited for a mobile electronics shop?
A Type A.
B Type B.
C Type C.
D Halon.
E All of the above are acceptable.
Answers
1 C,
2 A,
126
3 D,
4 A,
THE BASIC INSTALLER STUDY GUIDE
5 D,
6 A,
7 C,
8 A,
9 C,
10 D
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CHAPTER 3
INTRODUCTION TO AUTOSOUND,
SECURITY, WIRELESS & NAVIGATION
This chapter introduces you to the basic principles behind automotive
sound, security, wireless, and navigation systems. Its purpose is to give you
a better understanding of how these systems function and identify the terms
associated with these technologies.
The First Class level Study Guide is needed to understand these technologies
fully. This chapter is meant to be an introduction only, and includes only the
areas covered in the Basic Installer level exam.
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INTRODUCTION TO AUTOSOUND,
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Section 1
Introduction to Audio - Autosound Basics
Understanding basic acoustics will optimize your installation abilities.
Accordingly, the following section will provide you with a brief overview of basic
autosound principles.
Ask yourself – what exactly is a “sound”?
Sure, you know what “sound” sounds like – but what are the scientific properties
of sound?
✍ Sound is a type of
physical kinetic energy
called acoustical energy.
Actually, sound is a type of physical kinetic energy called acoustical energy.
■ Acoustical energy consists of alternating waves of pressure called sound
waves that travel through a physical medium such as air.
In order for a sound to be heard, two conditions must be present:
1 An object needs to be vibrating (i.e., a speaker cone)
2 And there needs to be an atmosphere through which the vibrations
can travel (i.e., air or water).
✍ A transducer is any
device that converts one type
of energy into another type
of energy.
✍ An audio signal is an
electrical representation
of a sound wave in the form
of alternating current (AC).
130
In a recording studio, for example, a vibrating object – like the strings on a guitar
or an artist’s voice initially produces sound waves. The sound waves may be
enhanced by the reflections and vibrations of the recording environment and
monitored by one or more microphones that work as transducers.
■ A transducer is any device that converts one type of energy into another
type of energy.
■ The transducer coverts the acoustical energy (sound waves) into
electrical energy (audio signal).
■ A microphone works the opposite of a speaker – instead of vibrating
the air, the air vibrates the diaphragm, which creates electrical energy.
An audio signal is an electrical representation of a sound wave in the form of
alternating current (AC). [SEE SECTION 1 OF CHAPTER 1 FOR A COMPLETE
DEFINITION OF AC.]
■ An audio signal is a complex combination of alternating periodic signals
called sine waves.
■ The frequency of the signal refers to the number of repetitions (cycles)
which are completed in one second. The more repetitions per second the
higher the pitch of the sound.
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The basic sound wave is comprised of four characteristics:
1 Frequency
2 Wavelength
3 Period
4 Amplitude
Margin Notes
1 CYCLE
1/2
CYCLE
AMPLITUDE
PRESSURE
+
0
—
TIME
PERIOD
WAVELENGTH
DISTANCE
■
Figure 60. Representation of a sound wave.
FREQUENCY
Frequency is the number of complete wave cycles that pass a particular point
each second.
■ The fundamental unit used to describe frequency is “cycles per second.”
■ This measurement is more commonly referred to by the term Hertz (Hz).
✍ Frequency is the number
of complete wave cycles
that pass a particular point
each second.
Example: A wave of 20 Hz would alternate from Point A to Point B, 20 times in
one second.
■ The higher the frequency, the more of these “vibrations” are packed
together in a one-second period. Frequency is directly related to the pitch of
the sound we hear.
1 Hz
3 Hz
1 second
■
Figure 61. Two separate wave cycles.
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Human hearing is considered to begin at 20 Hz, which is extremely low bass;
however, it can go as high as 20 kHz (or 20,000 Hz).
As shown in Figure 62, audio products are designed to reproduce frequencies that
the human ear is capable of hearing.
SUBSONIC
SUB
BASS
20
BASS
40
ULTRASONICS
LOWER
MID
RANGE
160
UPPER
MIDRANGE
MIDRANGE
320
2500
TREBLE
RANGE
5000
10000
UPPER
TREBLE
RANGE
20000
FREQUENCY (Hz)
■
✍ Wavelength refers to the
length of distance a single
cycle – or complete sound
wave – travels.
✍ Wavelength = Speed of Sound
Frequency
✍ When the frequency of a
sound wave increases, the
Figure 62. The range of human hearing.
WAVELENGTH
Wavelength refers to the length of distance a single cycle – or complete sound wave
– travels. You can determine this distance by dividing the speed of sound (1,130
ft./sec., at sea level on a standard temperature day) by the frequency:
Wavelength = Speed of Sound
Frequency
When the frequency of a sound wave increases, the wavelength decreases. In
other words, the higher the frequency, the shorter the wavelength.
wavelength decreases.
PERIOD
✍ The amount of time
required for a single cycle
of a sound wave is called
the period of the wave.
✍ Period =
1
The amount of time required for a single cycle of a sound wave is called the period of the wave. The period is expressed in seconds per cycle and is found by using
the following equation:
Period =
1
Frequency
Frequency
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AMPLITUDE
Margin Notes
Amplitude is the measurement of how powerful the waves are in terms of pressure.
Higher amplitude means higher volume in sound or higher voltage in electricity.
✍ Amplitude is the measurement of how powerful
the waves are in terms of
pressure.
AMPLITUDE
20
20K
FREQUENCY
■
Figure 63. Example of amplitude compared to frequency.
Sound is measured in Sound Pressure Level (SPL).
■ SPL is an acoustic measurement for the ratios of sound energy and is rated
using a unit called the decibel or dB SPL.
The ability to create louder sound requires high amounts of power. For example,
if you have a 100-Watt system at a certain volume and decide to double the power,
you will only notice a minor increase in volume (typically no more than 3 dB).
The decibel is a ratio and is used to compare ranges of measurements that are too
wide and require too many zeros to work easily.
■ To measure SPL, set “0 dB” at the point where a person with perfect hearing is barely able to hear a tone that is in the most sensitive “vocal” range of
human hearing. Sound pressure is then measured from that point near
silence to 140 dB, which is the human threshold of pain (but it is not the
upper limit of SPL).
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THE BASIC INSTALLER STUDY GUIDE
✍ SPL is an acoustic measurement for the ratios of
sound energy and is rating
using a unit called a decibel
or dB SPL.
✍ The decibel is a ratio and
is used to compare ranges
of measurements that are
too wide and require too
many zeros to work easily.
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Margin Notes
TYPICAL SOUND PRESSURE LEVELS OF VARIOUS SOURCES
140
130
120
110
100
90
80
Gunshot
50 HP Siren
Threshold of Pain
Recording Studio Monitors for:
Rock Music
Film Scoring
Loud Classical Music
Heavy Street Traffic
Subway
Cabin of Jet Aircraft (Cruise Configuration)
Alarm Clock
70
60
50
40
30
20
10
0
Average Conversation
Average Suburban Home (night)
Quiet Auditorium
Quiet Recording Studio
Soft Whisper
Extremely Quiet Recording Studio
Rustling Leaves
Anechoic Chamber*
Threshold of Hearing
(1 kHz to 4 kHz)
*Note that some anechoic chambers may be very noisy; the fact that a chamber does not
reflect sound internally does not mean it effectively blocks external sounds from entering.
Negative SPLs, while possible, are not given since, by definition, they are below the
threshold of audibility.
PHASE & POLARITY
✍ Phase is the time relationship of a sound wave to
a known time reference and
is measured in degrees from
0º to 360º (just like a circle).
134
Phase is the time relationship of a sound wave to a known time reference and is
measured in degrees from 0º to 360º (just like a circle).
■ When a loudspeaker pushes and pulls the air in front of it, it creates waves
of compressed air followed by waves of stretched air.
■ This is called compression and rarefaction, and correlates with the way
a sound wave or electrical wave is represented.
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As the wave moves outward from the loudspeaker, it exhibits characteristics that are important to producing sound.
■
■
Margin Notes
Figure 64. Example of rarefied and compressed air and corresponding sine wave.
Polarity, in this context, refers to the route electrons follow through the system –
from the positive terminal to the negative terminal.
■ Think of it this way, if you took two wires that were connected to a speaker and then reversed them, the resulting signal would be upside down. In
other words, the waveform would be the exact mirror image – so rather than
the cone moving outwards, it would be moving inwards.
■ This is called a polarity reversal and it is equal to a 180° phase shift.
■ Here’s something that catches a lot of people – a lot of installers state
something is “out of phase” when it is actually a polarity reversal (“out
of phase” is a matter of degree, polarity defines a condition).
One complete cycle of compression and rarefaction corresponds to 360º degrees.
■ If a speaker pushes and compresses the air in its very first motion and
then pulls, the wave would be considered “positive polarity.”
✍ Polarity, in this context,
refers to the route electrons
follow through the system –
from the positive terminal to
the negative terminal.
✍ One complete cycle of
compression and rarefaction
corresponds to 360º degrees.
If it pulls the air first and then pushes, it is considered to be “negative
polarity.”
■
The best way to determine polarity is with a test CD and a Polarity Checker. This
will not damage small speakers (like tweeters) and can be tested with the grille
covers in place.
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0°
90°
180°
270°
360°
POSITIVE HALF
NEGATIVE HALF
■
Figure 65. One complete wave cycle showing positive and negative phase.
If two speakers are mounted beside each other and both push and pull at the same
time, the speakers are considered to be in phase.
■ When in phase, the two (or more) speakers work together.
■ When all of the speakers do not do the same thing at the same time, the
speakers are considered to be “inverted” or having inverse polarity by 180º
degrees.
■ This situation occurs in unbaffled speaker installations. This tends to
cause destructive interference because what one speaker is trying to
produce, the other is fighting to cancel.
Destructive
Interference
+
■
136
Figure 66. Destructive Interference.
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If two speakers are mounted side-by-side but one is further forward than the other
(physical alignment), when the speakers are in phase, the wave from one speaker
will interfere with the other to some extent.
■ The two waves are not starting from the same point, even though they are
starting at the same time.
■ The sound will be out of phase anywhere from 1º to 359º degrees.
■ In Figure 67 (below), the signal is out of phase by 90º degrees. The
result is a new wave that’s both reduced in amplitude (due to interference) and at a different phase than its two parents. This occurs acoustically because you can only wire a speaker polarity to be 0º or 180º
degrees, depending on whether or not you reverse the two leads.
Margin Notes
In figure 66 (previous page), both speakers are wired identically; however, one is
moved ahead or behind the other by 25% of its wavelength (90º degrees is 25%,
or one-quarter, of 360º degrees).
■ If a 500 Hz tone is used, the wavelength would be 1130/500 = 2.26 feet.
One-quarter of 2.26 feet is .56 feet.
■ By moving one speaker behind the other by slightly more than six
inches, you would have a combined wave that is 90º degrees out of
phase.
■ Move it to 1.13 feet apart and the two tones would cancel each other
out (180º degrees).
Since we know that the wavelength of higher frequencies is shorter than low frequencies, manufacturers will often build home speakers that have the tweeters set
back slightly from the woofer so that the voice coils are aligned.
This is often referred to as time alignment, and it compensates for the different
sizes (lengths) of the wavelength.
✍ Time alignment compensates for the different sizes
(lengths) of the wavelength.
+
=
SUM OF 2 IDENTICAL
SIGNALS 90° OUT OF
PHASE
SUM OF 2 IDENTICAL
SIGNALS 180° OUT OF
PHASE
+
■
=
Figure 67. Sine wave example of front wave 90 and 180 degrees out of phase.
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Here’s how you can tell when a four-speaker, full-range system is out of phase (or
having most commonly an inverted polarity) by just listening:
1 Balance the system left to right.
2 If the bass is strong on one channel and weak on the other, and the
midrange and highs do not sound distinct, go to the amp (or head unit's
internal amp) and reverse the speaker lead on one side only.
3 Listen to the system again.
4 Balance left to right to see if the distance or “muddiness” has cleared
up and listen to see if the bass seems tighter. If so, the speakers could be
out of phase or have an inverted polarity.
Depending on you situation you could have a problem that is corrected simply by
reversing polarity electrically (this is a simple fix). If the problem is phase, you
could also have to change speaker position or location.
RESONANCE
All objects have a natural tendency to vibrate at certain frequencies.
■ A crystal wineglass, when tapped, will vibrate air to produce a tone somewhere between 2 kHz and 6 kHz.
■ The smaller the glass, the higher the pitch of the tone.
If you were to play a tone at the same frequency that the glass produces, the glass
would begin to vibrate on its own. This is known as sympathetic vibration and
is caused by the natural resonance of the object.
A bass drum will respond to frequencies around 30 Hz to 130 Hz. Playing a tone
in this range, and at a high enough volume, will cause the bass drum to vibrate
severely.
FREQUENCY RESPONSE
✍ Frequency response is
the relationship between
each individual frequency
and its amplitude.
138
Frequency response is one of the most important sonic measurements for determining quality. Frequency response is the relationship between each individual
frequency and its amplitude (this includes refraction and absorption, or constructive and destructive interference). To have a flat response, a system must
reproduce all frequencies in the human hearing bandwidth (20 – 20k Hz) with
equal amplitude.
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A waveform that has equal amplitude from low bass to high frequency (full bandwidth) is considered to have flat response.
■ A waveform with peaks and valleys is uneven in sound and can be annoying to listen to.
■ Irregularities in the midrange areas are quite noticeable – humans
are most sensitive at 1k Hz.
■ Peaks are much more noticeable than dips.
Margin Notes
✍ A waveform that has
equal amplitude) from low
bass to high frequency (full
bandwidth) is considered to
have flat response.
Therefore, choosing speakers that reproduce the entire audio spectrum smoothly
and without voids is crucial to the performance of the system.
■ The mounting of the speakers is equally critical to ensure the smoothest
possible bandwidth performance.
AMPLITUDE
AMPLITUDE
20
FREQUENCY
EXCELLENT RESPONSE
■
20K
20
FREQUENCY
20K
POOR RESPONSE
Figure 68. Example of excellent and poor frequency response.
In car audio systems, three things affect the linearity or smoothness of sound:
1 The vehicle’s size and shape cause resonance at certain frequencies
and cancellation of others at the seating position.
2 The materials used in the interior – such as glass, plastic and soft fabrics -- result in either reflections or absorption of the sound (they are
either constructive or destructive).
3 Road noise and other ambient noise will mask sounds, primarily in
the bass regions. But noise will not effect the linearity of the sound.
An equalizer can help control these external factors, but only after the original
acoustic causes have been identified and dealt with.
■ An equalizer should not be used as the only way to fix acoustic problems
that could have been taken care of with speaker placement, crossovers, gain
adjustments, etc.
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■ An equalizer should be used to compensate for personal preferences or
the differences in recorded material, not an obvious hole in the midbass or
a peak in the midhighs.
■ Excessive boosting of the equalizer controls can result in premature curving and can possibly damage speakers.
The human ear is very sensitive:
■ The ear is most sensitive to midrange, which is the human vocal region.
■
At low bass and high frequencies, the ear is less sensitive.
■ High frequency ability deteriorates with age (interestingly enough, women
retain their high frequency perception better than men.)
✍ Fletcher-Munson curves
depict the uneven frequency
response of human hearing.
In order to hear flat response, you must often boost the amplitude (volume) of the
bass and treble regions and reduce midrange to counteract what is known as
Fletcher-Munson curves which depict the uneven frequency response of human
hearing.
■ Overcoming this is most commonly achieved with the use of a graphic
equalizer. However, remember that the frequency response of any sound
system is affected by the environment in which it works.
Figure 69 (below) shows graphs called the Fletcher-Munson Equal Loudness
Contours. Using 1,000 Hz as a reference, they illustrate the relative levels that
must be produced acoustically to sound equally loud.
+100
100
+80
80
60
+60
40
+40
20
+20
0 dB
Threshold of Hearing
“An intensity level at which
sound just becomes
audible in an average
person with good hearing.”
10 Hz
■
140
100 Hz
0
1000 Hz
10 KHz
Figure 69. Fletcher-Munson Equal Loudness Contours.
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OCTAVES AND HARMONICS
Margin Notes
An octave is a musical interval between two tones formed when the ratio between
the frequencies of the tone is 2:1 (i.e., a doubling or halving of a frequency).
■ Unless it is an electronically produced pure tone, a musical note will have
overtones and harmonics.
■
A musical note has octaves that double the previous octave.
■ A note at a frequency of 440 Hz has octaves at 880 Hz, 1760 Hz,
3520 Hz, etc.
■ Each octave has eight full tones above and below another given tone.
✍ An octave is a musical
interval between two tones
formed when the ratio
between the frequencies
of the tone is 2:1.
■ Octaves also relate to the vocal range of a singer or musical instrument, as
in soprano, alto, tenor, basso, etc.
The fundamental frequency created by most musical instruments – with the
exception of synthesizers and pipe organs – is limited to about 8 kHz.
A harmonic is a weaker overtone of the original note (the fundamental frequency)
and is responsible for the character of the note.
When a musical note with a complex waveform has a distinct pitch (as opposed to
just plain noise), that waveform can be created by combining a set of precisely related sine waves. These sine waves are called harmonics. We recognize voices on the telephone because people sound different due to the harmonic content of their voices.
■ Harmonics occur at frequencies that are multiples of the original note.
■ A note at a frequency of 440 Hz may or may not have harmonics at
880 Hz, 1320 Hz, 1760 Hz, 2200 Hz, etc., and sub-harmonics at 220
Hz, 110 Hz, 55 Hz, etc.
✍ A harmonic is a weaker
overtone or undertone of the
original note (the fundamental frequency) and is responsible for the character of the
note.
If two instruments have exactly the same harmonic structure and strength, they
will sound identical. If only one harmonic is absent or significantly altered, a difference would be discernible to those with excellent hearing.
Speaker basics:
■ A basic speaker has a narrow frequency range, depending on the size of
the speaker cone.
■ Large speaker cones naturally produce bass, while small cones produce
higher frequencies.
Since a single speaker cone cannot cover all of the frequencies in the audible spectrum, manufacturers combine a larger bass cone with a small treble driver – or
tweeter – to more effectively cover the entire spectrum. The overall intention is to
improve the frequency response of the system to give you a flat response and
improve the sound quality.
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Special cabinet-style speakers have been designed to fill in the lower bass region,
these regions are difficult for virtually any vehicle to support.
■ Subwoofer systems are intended to accurately reproduce the sub-bass
region.
FUNDAMENTALS
OCTAVES
HARMONICS
SUB
HARMONIC
220 HZ
■
440 HZ
880 HZ
1760 HZ
3520 HZ
Figure 70. Examples of octaves, harmonics and their fundamental tone.
SIGNAL TO NOISE
✍ Signal to noise (s/n) is
a ratio that indicates how
much audio signal there
is in relation to noise,
under specific conditions.
✍ A high s/n ratio is always
preferable to a low s/n.
Signal to noise (s/n) is a ratio that indicates how much audio signal there is in
relation to noise, under specific conditions.
■ A high s/n ratio is always preferable to a low s/n.
■ This ratio of audio output level to the level of noise is expressed in
decibels (dB).
■ The s/n ratio usually begins at the noise level, whether high or low,
and goes to some arbitrary nominal level.
A musical note can be masked in a number of ways. Acoustically, the ambient
noise that occurs in the vehicle – as well as the road, wind, and traffic – will combine to mask the quieter musical passages. This is referred to as the “noise floor,”
and is concentrated mostly in the bass regions.
■ Many of today’s cars -- particularly the luxury cars -- do an excellent job
of lowering the noise floor by insulating the outside noises.
Electrically, the circuit noise present in electronic products will mask the very lowlevel signals that try to pass. The design of the product generally dictates how
noisy it will be.
■ When parts of lower grade (more economical) are incorporated into a design,
they will contribute to the thermal noise that infects the musical signal.
■ Quiet passages in the music will be covered by hiss.
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DYNAMIC RANGE OF A MUSIC RECORDING
Margin Notes
Dynamic range is the range of volume, in DeciBels from the softest to the loudest,
produced by a source of sounds. The reference is usually a musical selection, or
program signal being played.
■ A program is a structured, narrow band signal, while noise is a random,
wideband signal.
■ Rock and heavy metal music have a low dynamic range since the difference between the quiet lead guitar solo of 100 dB SPL and a full
crescendo of 130 dB SPL is only 30 dB.
■ Classical music can have a quiet flute solo of 60 dB SPL, followed by
a crescendo of 110 dB SPL that results in a dynamic range of 50 dB.
✍ Dynamic range is the
range of volume, in DeciBels
from the softest to the loudest, produced by a source of
sounds.
Even though the rock selection is louder overall, the classical selection has far
greater dynamic range.
HEADROOM
Headroom is one of those terms that are quite common in audio jargon. But ask
anyone to define headroom, and they’re at a loss. For once and for all, here is a
definition: In an audio device, headroom refers to the difference in levels between
the highest level in a given signal and the maximum level that the unit can handle without distortion.
■ Obviously, more headroom is desirable.
■ The music can have short peaks that are much higher in level than
the average signal level. For example, a musical crescendo consumes a
lot of power and can quickly push a system to its limits.
■ These short peaks are not registered by most audio level reading
devices and if the musical demand is higher than the system’s ability to
track it, the result is severe distortion (clipping) and probable damage.
✍ Headroom in an audio
device refers to the difference in levels between the
highest level in a given signal
and the maximum level that
the unit can handle without
distortion.
Think of headroom this way:
■ Imagine you’re jumping on a trampoline in a room with a low ceiling –
the consequences could be painful.
■ If you could raise the ceiling (add more “headroom”), then the
chance of hitting your head on the ceiling would be lessened.
In terms of a concert, the average sound level (100-110 dB SPL) is the nominal
program level.
■ The difference between the highest (peak) levels and the nominal level is
the headroom.
■ The classical music in the last section has more headroom than the
rock concert.
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■ Classical music is usually much more demanding on a sound system
than rock music just for these reasons.
90 dB Dynamic
Range
Maximum
Sound
Level
(Threshold
of Pain)
120 dB
SPL
30 dB
SPL
Ambient
Noise Level
20 dB
70 dB S/N
Ratio
Headroom
(dB SPL)
■
120
110
100
30
90
80
70
60
50
40
30
20
10
0
Figure 71. Dynamic range and headroom.
Autosound can be studied in greater depth in the MECP First Class Study Guide.
Section 2
Introduction to Security
When it comes to a security system, the system is only as good as its installation
– and you have a direct impact on the quality of the installation. Accordingly,
before getting to the basics, always be sure to follow these installation guidelines
for security systems:
■ Use caution in determining component locations.
■ If possible, refer to the vehicle’s owner’s manual to ensure the security system is installed in harmony with the other components on the vehicle (there
might be some major differences in the operating characteristics and wiring
compared to previous models).
144
■
Make sure all the connections are solid – use solder whenever possible.
■
Use a multimeter to check all wires – never use an incandescent test light.
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■
Figure 72. Typical security system.
BASIC COMPONENTS OF A SECURITY SYSTEM
Most security systems come with a variety of components that can perform many
different functions. The majority of systems you will be working with will include
the following parts:
■ Control unit
■ Siren
■ Switch triggers
■ Sensors
■ Engine disable(s)
■ Remote control
■ Accessory output devices
The Control Unit is the main element of all security systems. A control unit has the
electronic circuitry necessary to control all the functions of the security system. It
has the ability to arm and disarm, monitor triggers, and react to an intrusion.
Most control units also include circuitry designed to enable/inhibit the operation
of the engine. In addition, control units can include outputs designed to reflect
the status of the system. These can take the form of visual (LED outputs), or
Audible sometime referred to as “beepers”.
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✍ The Control Unit (sometime called the “Brain”) has
the ability to arm and disarm,
monitor triggers, and react
to an intrusion.
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■ Since control units are the central governing element, they are often called
the “brain” of the security system.
Control units chirp sirens, blink parking lights, and sound alarms in
response to commands or intrusions.
■
■ More sophisticated systems include multiple trigger inputs that enable
you to connect a different area of the vehicle to a different trigger input.
■ This allows the installer to divide up the vehicle into separate
“zones” for the purpose of easier system management and troubleshooting.
■ Some systems with multiple trigger inputs include a method to individually monitor and verify each trigger, sometimes called “diagnostics.”
■ This aids the installer or consumer in detecting and isolating a trigger-related problem.
SIRENS
The electronic siren is the most common form of sounding device found as standard equipment in today's automotive security systems. Usually, this device is a
self-contained unit consisting of three basic sections or stages:
1 The oscillator or tone generator stage
2 The amplifier stage
3 The speaker or output stage
The typical electronic siren can, therefore, produce its warning sound simply by
being connected to the proper power source.
Electronic sirens come in all shapes and sizes, but the most common is the bell or
horn shape.
■ The horn shape contributes to overall volume as well as pitch.
The outer casings of some sirens are composed of metal, but the great
majorities are made from various types of high temperature plastic.
■
SWITCH TRIGGERS
Switch triggers come in many different forms. The most common is the simple
spring-loaded pinswitch. Others include the roller push-button type, the magnetic reed switch type, metal pressure strip type, and the mercury tilt type. Each
of these types has advantages and disadvantages.
There are several types of triggering devices, we will cover just a few of the most
common ones:
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Spring-Loaded Pinswitch - This type of switch usually consists of a
spring-loaded plastic plunger set within a cylindrical metal housing that is
threaded at one end.
■
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■ Roller push-button - The roller push-button type is very similar to the
spring-loaded pinswitch except that instead of using a straight linear
plunger, it uses a ball or “roller” to push against an internal plunger and set
of contacts.
■ This feature makes it ideal for applications where a normal springloaded pinswitch would shear off, such as uneven surfaces and sliding
panels.
■ This switch is typically used to protect truck tailgates, drawers of
tool boxes, hoods, and other compartments that slide open.
Magnetic Reed Switch - The magnetic reed switch (also called a magnetic
proximity switch) uses magnetic force to cause a set of contacts to connect.
■
This switch basically comes in two parts: a switch and a magnet.
■ The switch contains a set of magnetic “reeds” or two thin flexible slivers
of metal, each with a contact at one end.
■ These reeds are enclosed inside a glass tube, insulated from each
other and attached to a stationary point at one end.
■ Each reed is connected to a wire, and each wire is run outside the
glass tube.
■ The whole switch assembly is typically placed inside a rectangular
plastic case.
✍ Magnetic reed switches
come in two basic electrical
forms: Normally Open and
Normally Closed.
SENSORS
Motion Sensors - A motion sensor is designed to detect motion – but what kind
of motion? The main purpose behind a typical motion sensor is to detect the
degree of motion a vehicle might undergo if it were being “jacked up” or if an
attempt was made to “tow” the vehicle.
■ These forms of “motion” usually consist of:
■ Gentle and nearly vertical up-and-down motions (i.e., those produced by a ratcheting jack), or…
■ A gradual change in the vehicle’s angle relative to the plane on which
it is parked (i.e., the change in angle that occurs when the front or back
of the vehicle is lifted for towing).
Shock and Impact Sensors - Shock and impact sensors are probably one of the
most common sensors in use in vehicle security systems today. They are typically
designed to detect the various degrees of impact that might be applied to a vehi-
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cle during a break-in attempt. Although they come in many different shapes and
sizes and operate on many different principles and designs, they all fit basically
into one category.
■ From the simple and primitive vibrating spring and contact type, to the
more exotic piezoelectric, these sensors basically work by detecting and
reacting to any shock, impact, or vibration applied to the vehicle.
■ Electromagnetic shock sensor detects vibration in the vehicle and transfers
it to a processor to trigger up to two different levels of output. This sensor is
usually referred to as a “two stage sensor”. These sensors can give a warning
trigger for a light impact on an automobile or causes the alarm to go into full
alert for a harder impact. The installer usually can set the impact level.
Figure 73. Electromagnetic Shock
Sensor.
■
Some sensor designs work better than others, since some are designed to better
sample and discriminate their inputs in order to avoid false alarms.
Sound Discriminators - The typical sound discriminator is designed for one single purpose – to detect and distinguish the sound of breaking glass. These sensors
are commonly called “glass sensors.”
Most sound discriminators consist of a microphone with frequency characteristics
that are weighted in favor of the frequency that glass produces when it breaks.
■ The microphone is connected to a filter/sampling network designed to further “discriminate” and select only the “signature” sound of glass breaking.
■ The circuit feeds into a comparator which compares the level of the sound
to the sensitivity threshold setting of the sensor, and then decides whether
to produce a trigger or not.
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■
Figure 74. Sound Sensor.
SOUND SENSOR
Spatial Sensors - The category of spatial sensors includes a variety of different
sensors that operate under different principles. The sensor's ultimate purpose is
to protect an area of “space” either in or around the vehicle or both.
■ The basic physical principles these sensors employ fall into three categories:
1 Ultrasonic
2 Radio field disturbance
3 Infrared field disturbance
Common names for these sensors include space sensors, microwave sensors,
Doppler sensors, mass sensors, and radar sensors.
1 Ultrasonic Type – The first “spatial” sensor to be used in a vehicle
security application was the ultrasonic sensor. This sensor usually consists
of two separate sections: a sender and a receiver. Extremely high frequency or ultrasonic sound waves are emitted from the sender unit and then
subsequently received by the receiver. Frequencies between 10,000 Hz
and 90,000 Hz are typically called “ultrasonic” frequencies. If there is an
object of sufficient mass moving within the area or “space” between the
sender and the receiver, it is detected and a trigger output is produced.
2 Radio Field Disturbance Type – Radio field disturbance is by far the
most common of the three types of spatial sensors.
■ These sensors operate essentially like the ultrasonic sensors in that
they also send out a signal and then monitor its return. However,
instead of using ultrasonic frequencies, they use even higher frequencies in the giga Hertz range, or more than 1,000,000,000 Hz (one billion Hertz). Radio frequencies in this range are also typically referred
to as “microwaves.”
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■
Figure 75. Radar Sensor.
3 Infrared Field Type – The infrared field type is less common in vehicle security applications than the other types of spatial sensors. However,
infrared sensors are used quite often in home and business security systems. Infrared sensors use light waves just beyond the visible red end of
the light spectrum known as the “infrared.” Infrared radiation is well suited to the task of spatial sensing.
■ An infrared field disturbance sensor is not subject to changes in air
pressure, so it will operate in a convertible or other open vehicle just
like a radio field disturbance sensor.
ENGINE DISABLES
The term engine disable includes any device that either prevents a vehicle's
engine from starting, or once started, prevents it from running for more than just
a short period of time. First, let’s take a look at the most common types. They
come in three basic forms:
1 Starter Disables
2 Ignition Disables (or diesel engine glow plug disables)
3 Fuel Delivery Disables
The manner in which these three forms of engine disables function are best
described by their names.
■ A starter disable works by interrupting or disabling the vehicle’s starter.
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■
Figure 75. Typical starter interrupt circuit.
■ An engine disable wired as an ignition disable, on the other hand, would
allow the thief to operate the vehicle’s starter, but since the ignition system
is disabled, the engine will fail to start.
An engine equipped with a fuel system disable would allow the starter to
operate and might allow the engine to start, but since the engine’s fuel supply is effectively cut off, the engine would run for only a short time.
■
REMOTE CONTROLS
Remote control security systems typically operate using technology that falls into
three basic categories:
1 Radio Frequency (RF)
2 Infrared (IR)
3 Inductive or magnetic
1 Radio Frequency Transmitters - By far the most common is the
radio frequency type, or simply RF. A remote control transmitter in a
security system using this technology uses radio waves of a specific frequency to operate the functions of the security system.
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■ The frequencies used by most brands of RF remote security systems
typically fall somewhere between 300 to 470 MHz.
This frequency band is also used by remote controls for some automatic garage door openers as well as some remote engine start devices.
■
2 Infrared - The second form of remote transmitter in use today is the
infrared. Unlike the radio frequency type transmitter, the infrared must
be used within line of sight of the vehicle. This is due to the fact that the
infrared radiation emitted by these units travels only in one narrow
straight line.
3 Inductive/Magnetic - The third form of remote transmitter is actually not a transmitter in the usual sense at all. These are typically referred
to as the inductive or magnetic type.
■ Instead of “transmitting” a signal, these units use the electrical property of inductance to arm and disarm a security system.
■ This is accomplished by passing the remote within just a few inches of
a special pickup usually located on one of the glass areas of the vehicle.
■ The “range” of these units is typically just a few inches.
ACCESSORY OUTPUT DEVICES
Accessory output devices incorporate circuits designed to control such things as
power door locks, power windows, power trunk/hatch releases, and garage
door/gate operation. These devices utilize basic building block components frequently used by installers such as relays, diodes, and timers.
✍ A relay is nothing more
than a switch with contacts
that are controlled by the
magnetic field from an
electromagnetic coil.
Relays - A relay is nothing more than a switch with contacts that are controlled
by the magnetic field from an electromagnetic coil.
■ Relays – like switches – are classified by the way their contacts are
arranged.
■ A relay may be designated a SPST (Single Pole Single Throw), or a
SPDT (Single Pole Double Throw), or one of many other configurations.
■ Due to these various contact configurations, a relay may be used
either to “make” a connection or “break” a connection, depending on
how it is wired.
Diodes - Another commonly used device may not be considered a “device” at all.
We’re referring to the simple semiconductor component – the diode. Diodes, like
relays, can help solve a vast number of installation challenges.
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A diode is nothing more than a one-way current valve. Voltage will flow through
a diode in one direction only; this property can be used to allow circuits to remain
isolated from each other and yet be connected to a common point as well.
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✍ A diode is nothing more
than a one-way current valve.
Diodes can be used to isolate or connect circuits of either power or ground polarity, depending upon the direction in which the diode is installed. Just remember,
a diode will block current flow in one direction, but allow current to flow in the
opposite direction. A less accurate but more understandable explanation of this
“one-way” action would be to say that when a diode is installed in a particular
direction, “power” will flow in one direction, but “ground” will not flow in the
same direction. In addition, the same diode will not allow “power” to flow in the
opposite direction, but it will allow “ground” to flow in the opposite direction.
Universal Timers - A “pulse” or universal timer can convert a momentary duration pulse from a security system or other source into a longer or shorter duration
signal to perform a variety of different tasks.
■ A timer might be used to create an interface between a remote security
system and the vehicle’s headlights. This would provide the driver of the
vehicle with a lighted pathway for a period of time long enough to allow
them to walk with a greater degree of personal security.
✍ A "pulse" or universal
timer can convert a momentary duration pulse from a
security system or other
source into a longer or shorter duration signal to perform
a variety of different tasks.
TELEMATIC SYSTEMS
Telematic systems have all of the benefits of a tracking system, but does not need
a full-fledged navigation system for their operation.
■ Telematics involve the creation and development of Intelligent
Transportation Systems (ITS) to track navigation, traffic volume, and safety
of private and commercial vehicles on roads and highways.
■ Many commercial bus and trucking companies use these systems.
A telematic system receives longitude and latitude information from GPS satellites
via a GPS antenna that’s concealed in the vehicle. The system then uses an embedded cellular phone connected to a wireless network to transmit vehicle status and
position information to a response center.
■ The driver can communicate with the response center by pressing a communications button.
■ Once connected to the response center, they can “see” the location
of the vehicle – longitude, latitude, speed and heading.
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■
The response center can provide a wide array of services:
■ Dispatch roadside assistance.
■ If the driver is lost, they can provide turn-by-turn directions.
■ If the keys are locked in the car, the driver can call the
response center and have the doors unlocked.
■ Some also offer a full range of concierge services, including
making reservations (for airlines, hotels, restaurants, etc.)
purchasing tickets or flowers, etc.
Most systems include a panic button for emergency situations
■ Thanks to the GPS capabilities, the response center can track a stolen
vehicle.
■
They can dispatch help in the case of an emergency.
■ The client can keep an in-depth, confidential medical history on-file
with the response center.
■ Once the panic button is pushed, the response center then “calls” the
vehicle to check on the driver.
■ During a car jacking, when instructed by the police, the response
center can cut off the ignition and unlock the doors, stopping the vehicle and providing access to the occupants.
■
If the battery level drops or goes dead, the response center can alert the driver.
■ Some systems include airbag deployment notification – if the vehicle is in
an accident in which the airbags deploy, the system automatically contacts
the response center.
BASIC INSTALLATION TIPS
The first installation rule to remember is that the ultimate success of any security system is directly related to the quality of its installation.
Putting this into perspective, if a pair of car speakers were wired “out of phase,”
the problem could probably go unnoticed by the majority of your customers. This
improperly installed system may be just an annoyance, nothing more serious. It
may not even impact the reputation of your company. However, an improperly
installed security system might awaken your customer and surrounding neighbors at 2:00 a.m. with false alarms. An improperly installed system may cause
electrical damage to factory wiring or fail to protect the vehicle.
The customer is placing a great deal of trust in you and your installation quality.
If a vehicle is damaged or stolen as a result of faulty installation, the owner will
feel betrayed by the installer and the shop itself. Not only will you have lost one
customer, but those future referrals that a “satisfied” customer will provide.
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Several physical and electrical factors can affect the overall quality of an installation. A few “do’s and don’ts” for any installation include the following:
1 Never begin a job without first reading both the Owner's Manual and
Installations Instructions Manual for the product.
Margin Notes
2 Inspect the vehicle for preexisting defects, and point them out to
your customer before you begin work.
3 When troubleshooting a malfunction or problem, observe the vehicle under the ambient condition in which the malfunction occurred.
4 Whenever possible, run wires alongside factory looms and cables.
This will make your work look “factory installed” and will significantly
enhance the overall security and durability of the system.
5 Always run a separate dedicated main power wire directly from the
vehicle's battery to the security system's main power lead. This can prevent many common sources of installation--created “failures,” such as
inductive load electrical noise.
6 Avoid using a simple incandescent test light to probe a vehicle’s
wiring. Incandescent test lights can damage sensitive vehicle computers,
as well as passive restraint systems, such as airbags. A digital multimeter
(DMM) is the safest way to test vehicle circuits.
7 Never connect power to, or operate, any system until all the wiring
connections have been completed.
8 Install wires in a secure fashion so they will not be susceptible to
damage from moving parts and will maintain their position over time.
9 Make sure that the proper wire gauges for the circuits and devices
installed are used.
10 Test every wire connection and circuit before moving onto the next one.
11 Always confirm that the “ground” points you select for use are truly
“ground.” A good ground connection will measure less than 0.1 Ohm.
12 Know what wires you are tapping into. Never tap into wires that are
coming from a “black box”: This may be a sensitive computerized device,
such as an engine control computer.
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13 When installing additional sirens to any security system, always connect the main (or first) siren directly to the security system’s output. Then
connect any other sirens (internal, external, or backup) through a Boschstyle relay. The relay power must be supplied from a separate fused wire
from the battery. This technique will ensure that the main siren will continue to function even addition sirens are shorted out or defeated.
14 Always make sure the mounting area of a device or component is safe
from contamination by water or heat, as well as from intentional damage
or unintentional damage by a mechanic performing routine vehicle maintenance.
These simple rules are ingrained in the minds of good installers. They have
learned over time that when you consider all the different consequences of the
installation during each step, the job goes smoother, works better, and best of all
does not come back!
Security Systems can be studied in greater depth in the MECP First Class Study Guide.
Section 3
Wireless Communications: The Basics of Installation
Cellular Installations
There are countless ways to install a cellular telephone. Accordingly, we do not
have the luxury of being able to cover each application. Therefore, we will cover
the basics.
As most of you already know, properly planning the installation will reduce the
number of unprofitable service calls.
■ A majority of all problems that occur with cellular telephones can be
traced back to installation problems.
TRANSCEIVERS
Transceiver is short for transmitter/receiver. It refers to a device that can both
transmit and receive signals.
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Mounting Location
The preferred location of the transceiver is in the trunk, even though most late
model transceivers can be mounted in various other places (including under the
front seat or under the rear seat; depending upon the type of car and manufacturer of the telephone).
■ If the transceiver is trunk-mounted, it should be securely mounted by
bolting the transceiver mount bracket to a suitable surface.
■ Pay attention not to puncture the gas tank or any other device.
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■ If the transceiver is mounted under the front seat, remove the seat and
bolt the mount bracket to the floor.
It’s extremely important that the transceiver be securely installed. If there is a collision, the transceiver could become a flying projectile that could cause severe injury.
Once the transceiver is securely mounted, the data cable, power cable, and antenna cable should be run from their location.
■ Be careful not to pinch the data cable or the antenna cable.
The antenna cable should have large radius bends to prevent the center
conductor from getting kinked or pinched.
■
The power cable can be sourced at the fuse box and should include the
appropriate fuse (check the install manual for the correct size).
■
Typical current draw of a 3 Watt cellular telephone is 1 - 3 Amperes during transmit, and from 0.1 - 1 Amperes during standby.
■ It’s a good idea to attach a card at the battery fuse that tells the owner to
remove the fuse when jump starting the vehicle.
■ Removing this fuse prevents the handset programmable telephone
from dropping its programming information due to a voltage surge,
which can occur when jump starting a car.
■ Removing the battery lead fuse also protects the telephone from
damage if the jumper cables are connected backwards.
✍ Typical current draw of a
3 Watt cellular telephone is
1-3 Ampers during transmit,
and from 0.1-1 Amperes
during standby.
The ground lead should be connected to a good chassis ground somewhere near
the transceiver.
The ignition lead can be hooked up to the ignition wire that does not lose power
during the crank position. This provides a good source that does not allow the
phone to cut off during cranking the automobile.
■ If you do not know which ignition wire to use, probe the suspect wires
with a Digital Multi-Meter to see which one is hot when the key is turned
on, and in the crank position.
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The data cable should be routed under the carpet, away from foot areas, to wherever the control unit is mounted.
■ Most telephones include a hands-free microphone and sometimes a separate hands-free speaker.
MICROPHONE
The hands-free microphone can be mounted almost anywhere, but there are a few
precautions:
■ If the microphone is mounted in the dash, make sure that the small holes
around the shell of the microphone are not blocked or plugged.
■ These holes are used for noise canceling, and the microphone will
not work correctly if it is flush mounted or the holes are plugged.
Since the wires inside the microphone cable are extremely small (usually
28-30 gauge), be sure that you do not pinch the cable or pull on it when
routing it behind the trim.
■
■ Make sure that the microphone is located as far away as possible from the
hands-free speaker. This will prevent feedback and allow the user to turn up
the volume of the hands-free speaker in order to hear the other person.
PERMANENTLY INSTALLED ANTENNAS
✍ At cellular frequencies, the
standard RG-58 cable that is
supplied with most cellular
antennas has a loss of about
3 dB over the 12-15 foot
length of the cable.
The majority of installation problems are the result of improper antenna installation.
■ At cellular frequencies, the standard RG-58 cable that is supplied with
most cellular antennas has a loss of about 3 dB over the 12-15 foot length of
the cable.
■ Any disturbance to the cable will cause even greater losses – such as
kinks in the cable or routing it next to a device that could cause static.
■ It’s extremely important to keep all bends to a minimum.
■ When bending the cable – such as the 90º degree bend that you use coming out of the headliner into the coupling box on a glass mount antenna –
use large radius bends.
■ Crimped-on connectors – whether they’re TNC or mini-UHF – must
be crimped on with a pair of antenna-connector crimping pliers made
specifically for the type of connector that you are using (see figure 77).
■ A regular pair of pliers will smash the outer braid against the dielectric,
forcing the outer braid to get close to or even touch the inside conductor.
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The distance between the outer and inner conductors determines the impedance
of the cable.
■ Impedance changes in the cable affect the Voltage Standing Wave Ratio
(VSWR), which in turn affects the transmission and reception of the signal.
■ A bad crimp can cause up to a 1 dB loss.
Margin Notes
✍ A bad crimp can cause up
to a 1 dB loss.
■
Figure 77. Special TNC crimping tool; a properly prepared cable.
When installing a glass-mount antenna (see figure 78), the antenna should be as
close to the top of the glass as possible.
■ This ensures that the phasing coil portion of the whip (or radiator) will be
as high above the roofline as possible.
■ The higher the antenna, the better the reception.
■
Figure 78. Glass-mounted antenna.
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Be careful when mounting a glass-mount antenna on glass that has a defogger or
FM antenna between the pieces of glass.
■ Always mount the coupling box so it is either centered between the defogger lines or above the defogger lines [grids] (see figure 79).
■ If you mount the antenna over the lines, the radio frequency (RF)
energy will be radiated into them, causing a substantial loss in power.
■ If the glass has a high lead content, such as Rolls-Royce glass, it’s
important to make sure that the antenna can perform correctly with
this type of glass.
■ The Antenna Specialists Company is one of the companies that
makes a device called the KAV-850 Capacitance Tester (see figure 80),
which tests the ability of a glass-mount antenna to transmit through
various types of glass.
■
Figure 80. Capacitance glass tester.
Figure 79.
Glass-mounted
antenna properly
installed between
defogger grids.
■
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If you like to paint antennas to match or contrast the car's color, keep one thing
in mind:
■ Depending on the paint used, this can cause up to 1 dB of loss due to dissipation of the radiation pattern caused by the metal content of the paint.
Margin Notes
When mounting the antenna, make sure that the whip is vertical.
■ If the whip is 30 degrees off vertical, there can be as much as 3-dB loss in
the radiated signal.
Mounting techniques, proper mounting locations, and the proper antenna are the
most important considerations when installing a cellular telephone.
HANDS FREE CAPABILITY AND INSTALLATION KITS
A more common type of installation is not having a permanently mounted cellular phone installed in the vehicle. The more convenient hand held versions are
readily available.
Several manufacturers have created adapters that allow hand-held phones to
operate in a hands-free manner.
■ These systems provide the benefits of a built-in car phone, with the added
advantage of flexibility that’s unique to portable phones.
This type of system consists of the following components:
■ Universal base unit – mounts near the driver and connects to the vehicle’s
electrical system as well as to the microphone and an external antenna.
■ The base unit contains a separate speaker so the driver can clearly
hear the conversation.
Installation for Hands Free Kits:
1 Install the base unit – choose a location so the base unit and the
phone are within easy reach of the driver and will not interfere with the
operation of the vehicle.
2
Install the wiring harness:
■ This is very similar to the permanent mount cellular phone wiring.
■ Connection to an unswitched power source (constant 12 volts positive).
■ Ignition connection, (switched) power.
■ Ground connection.
■ Microphone jack, usually to the wiring harness plug.
■ Do not route any cables near ABS or other electrical harnesses sensitive to radio frequency emissions.
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Margin Notes
3 Microphone installation is very similar to the installation of the hands
free microphone in the permanent mount cellular phone.
■ Position the microphone within 1 - 2 feet to the person speaking;
route the microphone wire so it is out of the way for safe operation.
4
Connect the cable from the external antenna to the base unit.
PROGRAMMING
Programming the cellular phone is critical to its operation. Each cellular phone
will have its own unique programming sequence. Please refer to the individual
manufactures programming instruction for guidance with this area of installation.
Wireless Communications can be studied in greater depth in the MECP First Class
Study Guide.
Section 4
Navigation Basics
Navigation systems are the latest frontier in the world of automotive electronics.
These systems are, in essence, a sophisticated navigation computer that’s installed
into the vehicle. Then with the aid of the U.S. government’s Global Positioning
Satellite (GPS) system, the driver is guided to his or her destination, or the vehicle can be tracked for the purpose of theft retrieval. This section will give the
installer the basics of navigation type technologies and there installation.
These systems can take on different configurations:
■ Stand-alone units.
■
Units that are integrated with the AM/FM/cassette/CD audio systems.
■ Units that have GPS/hybrid Wireless capabilities can provide two-way
communication to a response center.
■
Units that only provide verbal navigation commands.
■
Units that provide verbal and visual navigation commands.
■ Some can be accessed via a wireless remote control.
In essence, the goal of vehicle navigation systems is to do away with conventional road maps by providing the driver with a system that plots the quickest route
from Point A to Point B.
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TYPES OF NAVIGATION
Margin Notes
Presently, there are four basic navigation systems in the marketplace:
1 Voice activated.
2 Telepath™.
3 GPS locators.
4 Advanced Route Guidance systems.
Voice Activated
The first voice activated navigation systems reached the market in early 1995.
■ A voice activated system operates via a specially designed CD or DVD that
contains a database of roads, highways, landmarks and thousands of points
of interest (POI).
■ Each street name, highway, city and POI has been recorded on the CD.
■
The CD or DVD is loaded into a specially designed changer or player.
■ The user can activate the system via microphone mounted in the car by
saying a specific word like, “Navigator.”
■ The voice activated system then asks a series of questions like:
■ Where are you starting from?
■ Where do you want to go?
■ The system then gives you verbal commands, “Where to go next.”
Telepath™
This system was developed by Delco Electronics (a division of General Motors).
■ Telepath uses the GPS signal to find its current location.
■
The user inputs their destination via a small LCD type display.
■ Destinations can be entered via address, intersection, or landmark
(such as “ATM” or “GAS”).
GPS Locators
GPS Locator systems utilize a “moving map” on a video screen in the vehicle to
direct the driver.
■ This system utilizes a digitized map of a specific area with “hidden” longitude and latitude coordinates.
■
The system incorporates a GPS receiver.
■ The GPS receiver must receive at least three GPS satellite signals to
determine the correct longitude and latitude coordinates.
■
The GPS information is then compared to the digitized map data.
■ When the current location is found on the map, that image of the
map is displayed on the screen.
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These systems rely only on the GPS signal to find the location of the vehicle.
■ The U.S. government only guarantees GPS accuracy up to 300 feet, which
can easily lead to errors on the map.
■ This system does not take into account vehicle speed or direction,
therefore, turn-by-turn guidance is not completely accurate.
This system can show the driver their destination on the digitized map,
but it’s up to the driver to figure out how to get from Point A to Point B.
■
Advanced Route Guidance Systems
This type of system utilizes three different input sensors to determine the present
location and track the progress of the vehicle:
1 GPS antenna/receiver – uses GPS satellites to determine the current
position of the vehicle.
2
Gyro sensor – determines the direction in which the vehicle turns.
3 Vehicle Speed Sensor (VSS) – determines how far and how fast the
vehicle has traveled.
Thanks to the gyro sensor and speed sensor, these systems more accurately display the vehicle’s position and track the vehicle’s progress – even when driving in
areas where the GPS signal may be blocked
Here are the basic elements of an advanced route guidance navigation system:
1 Main navigation ECU – the “brains” of the navigation system.
Includes a built-in gyroscopic sensor, speed pulse sensor, Global
Positioning Satellite receiver, and DVD or CD-ROM drive. It processes:
■ The incoming data from the vehicles speed sensor.
■ The speed of the vehicle.
■ The direction coming from the gyro sensor.
2
164
GPS antenna – receives incoming satellite signals.
■ Antenna has a small footprint and some have a magnetic base.
■ Designed to be mounted with inside applications as well as outside
of the vehicle.
■ Antenna must have a clear view to the sky to receive satellite information.
■ GPS reception can be slightly reduced when the antenna is mounted inside the vehicle.
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3 CD-ROM’s or DVD’s– contain the maps for each locale (which can
be updated periodically).
■ Some companies rely on universal mapping software.
■ Other companies provide customized DVD or CD-ROM discs.
■ DVD has the ability to store entire countries.
■ On some systems, when you install the system, you have to install the
correct CD for your geographic area – it’s not like changing music CDs.
■ Other systems allow you to swap CDs when you change geographic
areas.
■ Use care when handling the DVD or CD-ROM.
■ When the DVD or CD-ROM is removed from the ECU, place it in
the supplied jewel case.
■ Do not expose to extreme heat.
4
Margin Notes
Video monitors – displays directions.
Some monitors include a built-in speaker.
■ Has to be mounted within view of the driver.
■ If customer is concerned about theft, some monitors are available
with quick release brackets.
■ Some monitors can be used to interface and control the audio system.
■ Most monitors allow the driver to “zoom in” and “zoom out” to show
more or less detail on the map.
■
5 Remote control – many systems include a wireless remote control to
help operate the navigation system.
Basics of Installation
There are countless ways to install a navigation system. Accordingly, we do not
have the luxury of being able to cover each application. Therefore, we will cover
the basics.
As most of you already know (and as we discussed in Chapter 2), properly planning the installation will reduce the number of unprofitable service calls.
■ Over 80% of all problems that occur with navigation systems can be
traced back to installation problems.
Following are the basic guidelines you should follow when installing an Advanced
Route Guidance Navigation System.
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Mounting the ECU
On some systems, the main navigation computer is designed to be mounted in
the trunk; on others, it can be mounted in the trunk or the glovebox (depending
on available space).
■ Find a suitable location for the ECU.
■ Avoid any moving parts, places where moisture can arise, or locations near extreme heat.
■ Locations such as under the front seats, or hanging from the rear
package tray work the best.
■ The ECU must be mounted horizontal (less than 5°).
The gyro sensor mounted inside the ECU will not work properly when the unit
is mounted on its side.
Mounting the Antenna
The GPS antenna needs to be mounted in a location that is the most “visible” to
the GPS satellites. Therefore, you need to carefully plan the location. When determining the mounting location, follow these guidelines:
■ Do not mount under any metal surface.
■ Some window tinting material has a high metal content (titanium),
which can reduce the GPS antenna’s reception.
■ Some newer vehicles – like the Oldsmobile Aurora – incorporate
special heat resistant glass that will cause GPS reception problems.
■ For those situations, it’s best to install the GPS antenna on the roof
or the rear trunk lid.
■ Mounting the antenna under dense plastics or cardboard may inhibit
reception.
■ The GPS antenna can receive the needed signals when mounted inside the
vehicle, but some precautions must be taken to ensure proper performance:
■ Mount the antenna in a location in the vehicle that allows the best
“line-of-site” performance. Locations such as the rear package tray or
front dash work the best.
■ Secure the antenna with double sided tape or silicone.
■ This helps prevent the magnetic base from moving and scratching
the paint.
■ Carefully route the antenna cable and connect it to the ECU.
■ The cable is matched to its length – do not shorten or extend.
■ Avoid making sharp bends in the cable.
■ Wind excess cable into large loops.
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MOUNTING THE MONITOR
Margin Notes
Like most installations, you have to plan out where you want to install the monitor. It’s needs to be convenient, yet unobtrusive – you don’t want it blocking any
of the vital controls.
■ If possible, talk with the customer to hear their thoughts on where they
want to mount the monitor.
Try to mount the monitor so the driver can see the monitor without too
much distraction.
■ If the monitor will be mounted low, angle it up for best performance.
■ Always check with the customer before drilling holes to ensure the
location works for them.
■ You may want to tape the monitor in place to ensure the client likes
that location and that it’s not awkward or in their outward line of sight.
■ Do not mount the monitor where it could be struck by an airbag in
the event on an accident.
■
Once the installation is complete, adjust the monitor’s brightness level for best
performance.
■ Most monitors have a separate brightness adjustment for day and night
viewing (when you turn on the parking lights, the display dims).
Most monitors come with a fixed length of cable that cannot be extended. Keep
this in mind when routing the monitor cable to the ECU.
WIRING
Wiring most navigation systems is about as simple as wiring a cellular phone or a
head unit.
■ Typically, there are only six wires to connect on the main harness.
■ If there are any remaining wires, they are usually used to connect the navigation system to the audio system.
SAMPLE WIRING CODES
Yellow..........................................Battery (+)
Black............................................Ground
Red ..............................................Ignition (+)
White/Blue ..................................Illumination (+)
Orange/White..............................Reverse Lights (+)
Green/White................................Vehicle Speed Sense (VSS)
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Margin Notes
In general, the basic connections for power, ground, ignition and illumination
should be very straightforward.
■ The reverse light input is a necessary connection. The navigation unit
must know when the vehicle is driving in reverse, so it can compensate
when determining the precise location of the vehicle.
■ It can typically be found at the transmission switch, the main wire
harness that runs to the tail lights or at the reverse light itself.
The most difficult wire to find will be the VSS wire.
■ Some manufacturers, have a special Application Support team that helps
installers locate the VSS wire.
Caution: Some older vehicles may not have VSS wires. Under those circumstances, you must install a speed pulse generator onto the speedometer cable.
VEHICLE SPEED SENSOR TESTING AND VERIFICATION
Once the Vehicle Speed Sensor (VSS) has been installed, you have to test to make
sure it is functioning, and then verify its accuracy. There are two types of Vehicle
Speed Sensors:
1 Analog
2 Digital
Analog VSS
NOTE: If you’re working with an analog VSS, DO NOT hook up the analog speed
pulse wire to the navigation system before undergoing the initialization process.
Analog speed pulse is measured as AC voltage with reference to chassis ground.
■ Due to varying AC voltages and frequencies, the only accurate way to verify an analog speed pulse is to use an oscilloscope.
■ If you do not have access to an oscilloscope, verify that the wire does
not have a positive DC voltage by using your digital multimeter.
■ Next, set your digital multimeter to AC voltage at the 30-volt range
or on auto-range.
■ Connect the black lead of the multimeter to chassis ground.
■ Probe the speed pulse wire with the red lead.
■ The meter should read zero volts.
■ Start the car and drive slowly (you should have someone riding with
you to read the multimeter while you drive).
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The meter should slowly begin to show an increase in voltage.
■ At slower speeds, the voltage should be approximately 2 - 5 volts AC.
■ As vehicle speed increases, AC voltage will increase.
■ Maximum AC voltage should be somewhere around 5 - 8 volts at 60 mph.
Margin Notes
Do not confuse this process with checking the tachometer wire. The tachometer
wire increases voltage with the engine’s RPM. The speed pulse wire increases voltage with the vehicle's actual speed.
After verifying the analog speed pulse wire, you must follow certain procedures to
initialize the navigation system to accept an analog speed pulse prior to attaching
the wire to the system.
■ Check the manufacturer’s installation instructions for the proper procedures.
Digital VSS
To test and verify a digital VSS, you will need a digital multimeter set to DC Volts
at the 30-volt range or on auto-range.
■ Be sure to question the customer so you understand the powertrain layout of the vehicle.
■ For front-wheel drive, jack up only one of the front two wheels.
■ For rear-wheel drive, jack up only one of the rear wheels.
■ For all-wheel drive vehicles, you will need to jack up all of the drive
wheels (if you cannot switch to 100% rear-wheel drive or 100% frontwheel drive).
■ For 4-wheel drive vehicles that drive only the rear wheels when in
2-wheel drive mode, jack up only one of the rear wheels.
■ For vehicles with a locking differential, you will need to jack up both
(or all) of the drive wheels.
■ Be sure to block the remaining wheels to prevent the vehicle from
rolling.
■
Connect the Black lead of the multimeter to chassis ground.
■
Probe the speed pulse wire with the Red lead.
■
Turn the ignition key to the “ON” position, but do not start the vehicle.
■
Read the multimeter.
It should show zero volts (off) or a voltage ranging from 5 - 12 volts (on).
■ The voltage range will differ depending upon the vehicle, however it will
not fluctuate.
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Margin Notes
■
Rotate the tire slowly.
■ The voltmeter should change state between zero volts (off) and 5 - 12
volts (on) or vice-versa within 2-3 rotations of the tire.
That is all you have to do to verify the digital speed pulse.
TESTING THE SYSTEM
Unlike your typical installation, a navigation system is not fully functional the first
time you switch it on. For example, you have to allow the ECU time to get “in
sync” with the GPS satellites.
Follow these guidelines:
■ Park the vehicle in an area outside where the GPS antenna has good
reception.
■ Make sure the vehicle is away from tall buildings or trees.
■
Turn on the unit.
■ This process takes between 10 and 30 minutes while the system
receives the GPS data and finds the approximate vehicle location.
■
Once the unit “wakes up,” typically a disclaimer screen will appear.
■
Press the “ENTER” button.
■
The map screen should appear.
■ In some instances, the vehicle icon may appear on a blank map
screen (no roads are illustrated) – this condition is normal.
■ Somewhere on the screen will be a GPS signal icon (it should be in the
shape of a satellite).
■ Once the unit receives the GPS data, the GPS icon will change (in
some instances, it will change color – from dark gray [no reception], to
light blue [minimum reception], to yellow [maximum reception]).
The vehicle icon should now be visible on the map, and the monitor should show
the approximate vehicle location.
Don’t worry if the map position is a block or so away from your actual position –
the system will correct itself as you drive.
These are only basic guideline for installation. For further guidelines consult the
individual GPS manufacturer.
Navigation Systems can be studied in greater depth in the MECP First Class Study Guide.
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Margin Notes
SAMPLE TEST QUESTIONS
1
At what frequency is the human ear most sensitive?
A 25 Hz to 35 Hz.
B 100 Hz to 250 Hz.
C 1000 Hz to 2000 Hz.
D 15000 Hz to 20000 Hz.
2
What is sympathetic vibration?
A Noises made by processors.
B The natural resonance of an object.
C Distortion.
D Ignition noise.
3
An audio signal is an electrical representation of what?
A Sound Wave.
B Octave.
C Potentiometer.
D Inductance.
4 Destructive interference refers to two speakers whose sound waves are working against each other and our out of phase by:
A 45º degrees.
B 90º degrees.
C 180º degrees.
D 270º degrees.
E 360º degrees.
5
A Magnetic Reed Switch, also called a magnetic proximity switch:
A Uses magnetic force to cause a set of contacts to connect.
B Uses kinetic energy to open and close a set of contacts.
C Has input for multiple switch triggers.
D Can replace the use of a relay.
6
The most common used device to interrupt a vehicle’s starter is a:
A Electronic switching capacitor.
B Heavy duty diode.
C Electromagnetic switch.
D Pulse timer.
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Margin Notes
7 Is an impact sensor the best device to detect breaking glass during a break in
attempt?
A True
B False
8
A “pulse” or universal timer can be used to:
A Remove unwanted EMI from you security system.
B Add a pulsed output for alternating flashing parking lights.
C Convert a momentary duration pulse into a longer or shorter duration
signal.
D Reverse the pulse from negative to positive for door triggers.
9
A glass mount antenna will transmit and receive best:
A When mounted over two defogger grids.
B When it is mounted over an FM antenna grid.
C When mounted between or above the defogger grids.
D When place at a 45º degree angle to the ground plane.
10 Extending the length of the RG 58 coax cable supplied by the manufacture
(normally 12-15 feet) can result in as much as 3 dB of signal loss.
A True
B False
11 The small holes on the side of the hands free microphone are commonly
used for:
A Decoration.
B Noise canceling.
C The mounting clip.
D Have no specific purpose.
12 Painting cellular antenna mast with car paint can typically cause up to 1 dB
of loss.
A True
B False
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Margin Notes
13 Which of the following materials will not attenuate the signal from a GPS
antenna:
A Metallic window tint.
B Line defrosters.
C Electrically heated windshields.
D Factory pigment tinted glass.
14 The best choice of mounting position for the GPS antenna is:
A Under the trunk lid.
B Under the hood.
C Under the headliner.
D On the rear deck or dash.
E On the center console.
15 The length of antenna cable on a GPS receiver is;
A Unmatched.
B Preset.
C Random.
D Uncorrelated.
16 A true VSS signal will vary in proportion with;
A Engine temperature.
B Engine RPM.
C Ignition voltage.
D Battery voltage.
E Vehicle speed.
Answers
1 C,
2 B,
11 B 12 A
3 A,
13 D
4 C,
5 A,
6 C,
7 B,
14 D 15 B 16 F
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9 C,
10 A
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Glossary of Terms
GLOSSARY OF TERMS
GLOSSARY OF TERMS
Margin Notes
ABC
AC (Alternating Current) – Energy that alternates back and forth at a certain frequency. The frequency is measured in hertz. In automobiles, AC is produced by
the alternator and then rectified to DC.
Acoustical Energy – Energy consisting of fluctuating waves of pressure called
sound waves.
Acoustics – A science dealing with the production, effects, and transmission of
sound waves through various mediums.
Active Arming – A method for arming a security system that requires some action
by the driver/operator. This action could include pressing a button on a remote
transmitter or entering a code on a keypad.
Air Horns – A type of horn that uses compressed air instead of an electric
diaphragm or voice coil to produce sound. These horns are usually driven by an
electric air pump that receives its trigger from a host security system.
Alarm Reset – The property of an alarm system that resets the alarm to an
alarmed state after a pre-determined period of time.
Alarm Re-triggering – A condition that occurs in a security system that has been
triggered. Instead of sounding the siren for its designated time interval, it is retriggered and made to sound again.
Alternator – A mechanically driven automotive device that generates DC power;
it is the primary source of vehicle power.
Alternator Whine – A siren-like whining that occurs when an engine’s RPMs
increase. The noise is usually the result of a voltage differential created by more
than one ground path or a poor ground path.
Ambience Synthesizer – A unit that produces an artificial ambience pattern; one
that is used to create the impression of the listener and/or performer being in a
particular performance space.
Ammeter – An instrument used for measuring the amount of current flowing in
a circuit.
Amperage – A unit of electrical current; the force through which the energy is
pushed through a conductor. Measured in amps; Ohm’s Law symbol is I.
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GLOSSARY OF TERMS
Ampere – The unit of measurement used to determine the quantity of electricity
flowing through a circuit. One ampere flows through a 1 Ohm resistance when a
potential 1 Volt is applied.
Margin Notes
Amplification – An increase in signal level, amplitude, or magnitude.
Amplitude – The measure of how powerful sound waves are in terms of pressure.
Amplitude Modulation (AM) – A method of modulation in which the amplitude
of the carrier voltage is varied in proportion to the changing frequency value of an
applied (audio) voltage. (See also Frequency Modulation)
Analog – An electrical signal in which the frequency and level vary continuously
in direct relationship to the original acoustical sound waves. Analog may also refer
to a control or circuit which continuously changes the level of a signal in a direct
relationship to the control setting.
Analog Switch – A hardware-oriented switch that only passes signals that are
faithful analogs of transducer parameters.
Anode – The electrically positive pole of an electronic device such as a semiconductor. A diode, for instance, has a positive and a negative pole; these are known
as the anode and the cathode.
Antenna – A mechanical device, such as a rod or wire, that picks up a received
signal or radiates a transmitted signal.
Arm – The term used to describe the act of causing a security system to reach a
state in which it will protect the vehicle.
Arming Delay – A term used to describe the elapsed time between the moment
a security system is first told to arm and the moment it is actually armed. This
normally applies only to systems that are passively armed, but it can apply to
actively armed systems, as well.
Attenuate – To lessen the amount of force, magnitude, or value of something.
Audio Frequency Spectrum – The band of frequencies extending roughly from
20 Hz to 20 kHz.
Audio Oscillator – A device that produces tones at specific frequencies for testing either equipment or entire systems.
Audio Signal – An electrical representation of a sound wave in the form of alternating current (AC) or voltage.
GLOSSARY OF TERMS
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Margin Notes
Auto Reset – The ability of a security system to automatically reset itself after
being triggered.
Back-up Battery – A separate battery added to the security system as an alternate
power supply to serve as a backup in case the vehicle’s main battery is disabled by
a thief. Back-up batteries are typically the lead-acid gel cell type and are most
effective when hidden from detection.
Ballast Wire – The name given to a special resistance wire used between the ignition switch and the engine’s high voltage coil.This wire is typically composed of a
carbon compound instead of normal copper.
Bandpass Filter – In mobile electronics, a device which incorporates both highpass and low-pass filters in order to limit and attenuate both ends of the frequency range.
Bandwidth – Refers to the “space” in the frequency response of a device through
which audio signals can pass (between lower and upper frequency limits, those
points where the signal level has rolled off 3 dB).
Bass – The low audio frequency range, normally considered to be below 500 Hz.
Bass Reflex – a vented enclosure that allows control of rear radiated sound waves.
Battery – A device that stores electrical energy. A battery makes direct current
through a collection of cells.
Bias – An unbalanced sound level.
Boomy – Usually refers to excessive bass response, or a peak in the bass response
of a recording, playback, or sound reinforcement system.
Bridging – Bridging combines two channels of an amplifier to turn it into a one
channel amplifier.
Brain – The common term used to refer to the main control unit of a security system. (See also Control Unit)
Butterworth Filter – A filter with a pass-band with no ripple but usually sacrifices some steepness in attenuation.
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GLOSSARY OF TERMS
Capacitance – The property exhibited by two conductors separated by a dielectric, where an electric charge becomes stored between the conductors. (Also see
Farad.)
Margin Notes
Capacitor – An electronic device that stores energy and releases it when needed.
Also used to direct high-frequency energy to tweeters. Rated in Farads.
Cathode – The electrically negative pole of an electronic device such as a semiconductor.
CDPD (Cellular) – Cellular digital packet data. Digital data non-voice two-way
communications transmitted in the cellular band.
Cell – A single unit for producing DC electricity by electrochemical or biochemical action. A common vehicle battery is composed of a number of individual cells
connected together. Each cell is typically rated at 2.11 volts; a common 12VDC
automotive battery is composed of six separate two-volt cells.
Cellular Telephone – A device consisting of a control unit, a transceiver, and an
antenna that processes calls to be sent to or received from the cellular system.
Channel (Cellular) – A frequency or band of frequencies assigned to a station or
communications system. Also, a sub-circuit of a larger system (e.g., voice channel, control channel, paging channel).
Channel (security) – The term used to describe the number of different functions possible for manipulating the buttons on a remote control transmitter.
Chassis – The metal frame of the vehicle.
Chebyshev Filter – A filter that has some ripple in the pass-band but has an initial attenuation slope which is steeper than a Butterworth filter.
Chirp – The term used to describe the brief sounding of a security system’s siren
designed to indicate the state of arm of the system.
Circuit – A closed path through which current flows from a power source,
through various components, and back to the power source.
Circuit Breaker – An electromechanical device designed to quickly break the
electrical connection should a short circuit or overload occur. A circuit breaker is
similar to a fuse, except it will reset itself or can be manually reset, and will again
conduct electricity.
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Margin Notes
Clipping – Distortion that occurs when a power amplifier is overdriven. This can
be seen visually on an oscilloscope, when the peaks of a waveform are flattened,
or “clipped off,” at the signal’s ceiling.
Closed Circuit – A continuous unbroken circuit in which current can flow without interruption. Also known as a closed loop.
Closed Loop – A feedback path in a self-regulating control system. Unlike a standard open state trigger that needs to have a connection established to serve as a
trigger, a closed loop trigger will act to trigger a security system when its loop
(connection) is broken.
Closure Wire – The name given to describe a wire found on some vehicles that,
when given a certain duration input, will cause the doors to lock and the windows/sunroof to close.
Code – The aspect of a security system that can be tailored by the manufacturer
or the installer to personalize the particular system for a user or group of users. A
remote security system that is coded will operate only with those transmitters that
are coded to the same code.
Coaxial Speaker – A coaxial speaker has a large cone for the low range and a smaller tweeter for the high spectrum. There is a crossover network that divides and
routes the signal to the correct driver. Named for two speakers sharing a single axis.
Co-Linear Antenna – An antenna that uses a phasing coil to electrically connect
stacked elements in the proper phase relationship.
Compliance – The measurement in liters or cubic feet of the volume of air that is
equal to the compliance of a speaker’s total suspension.
Cone – The most common shape for the radiating surface of a loudspeaker. Often
used to refer to the part of the speaker that actually moves the air.
Control Unit – The central processor for a security system.
Constant Output – An output of a security system that provides a constant or
continuous output to drive a device. Often used for sirens and engine interrupts.
Control Unit – The central processor for a security system. (Also see Brain.)
Coulomb – An amount of electrical charge which contains 6.24 x 1018 of electrons.
Crossover – A device that separates the different frequency bands and redirects
them to different components.
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Crossover Frequencies – The frequencies at which a passive or electronic
crossover network divides the audio signals, which are then routed to the appropriate speakers.
Margin Notes
Crossover Network – A unit that divides the audio spectrum into two or more
frequency bands.
Current – The rate of electrical or electron flow through a conductor between
objects of opposite charge. Symbol I, measured in amperes or amps.
Current-fed Antenna – An antenna in which the feeder or transmission line is
attached to the radiator at a current loop. This type of antenna requires a ground
plane.
Current Sensing – A name given to a form of alarm system trigger that relies on
sensing a change in the power supply of the vehicle. More accurately called voltage sensing, this feature is found on many inexpensive alarms.
DEF
Damping – The reduction of the magnitude of resonance by the use of some type
of material. The damping material converts sound to energy, then disperses the
energy by converting it to heat.
DAT – Digital Audio Tape.
DC – Direct Current. A flow of electrons that travels only in one direction.
Decibel (dB) – The standard unit of measurement used to indicate the relative
intensity of sound.
Dedicated Fuse – A fuse designated to supply power and protection for one particular circuit only.
Destructive Interference – A phenomenon that occurs when speakers are 180
degrees out of phase. For example, what one speaker is trying to produce, the other
speaker is fighting to cancel. One speaker’s wave is in the positive phase (compression), while the other speaker’s wave is in the negative phase (rarefaction).
Diaphragm – A thin metal or dielectric disk used as the vibrating member in
loudspeakers. Also known as a cone.
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Margin Notes
Difference of Potential – The algebraic sum of voltages at two points of different
electrical potential.
Diode – A two-electrode (two-terminal) device that allows a voltage/signal to pass
through it in one direction only.
DIN – Deutscher Industrie Normen. German industrial standards that are used in
many European countries. DIN size refers to the stereo size that fits most
European cars.
Disarm – The opposite of arm, or the term used to describe the action of placing
a security system in an inactive or standby mode.
Distortion – Sound that is modified or changed in some way. In a speaker, distortion is produced by several factors, many of which are related to poor construction. Voice coil rubbing (caused by being overdriven) is the most common
cause of distortion.
DMM – Digital Multimeter. A digital meter that gives a precise reading of voltage,
current, or ohms. This type of meter “samples” the input and feeds it to a digital
readout.
Dolby System – A unique patented noise reduction system that electronically
eliminates the irritating noise (tape hiss, circuit noise, etc.) without sacrificing the
original tonal quality.
Dome Light – The common term used to describe the overhead (or headliner)
mounted interior courtesy light.
Door Lock Solenoid – The proper name for the electric bi-directional actuator
used to provide powered control of vehicle door locks. Also called a Door Lock
Actuator.
Doppler Sensor – Another name for a spatial type sensor, also commonly called
a radar sensor.
DPDT – Double Pole Double Throw. A term used to describe a relay that has two
separate poles or contacts and can throw or make electrical contact with two separate stationary contacts.
Dress – The arrangement of signal leads and wiring for optimum circuit operation, cosmetic appeal, and protective routing.
Driver – Another term for a loudspeaker. Often used when the loudspeaker is
coupled with a horn for acoustic coupling and controlled dispersion of sound.
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DSP – Digital Signal Processing (or Processor). A type of processing accomplished
by a micro-computer chip specifically designed for signal manipulation, or a component using such processing. The term is often misused as a synonym for ambience synthesizer; however, DSP can do much more than sound field creation.
Margin Notes
Duty Cycle – An engineering term used to describe the actual time (or frequency)
that a circuit or device operates. A pulsing alarm output that is on for seven-tenths
of a second and off for three-tenths of a second would have a 70% duty cycle.
Dynamic Range – The range difference between the quietest and the loudest passages of the musical selection or program signal being played.
Efficiency – The measurement of a loudspeaker’s ability to convert power to
work. Formula: Efficiency = (power out/power in) x 100. Efficiency is always
expressed as a percentage.
Electrolyte – The name for the mixture of diluted sulfuric acid found in standard
lead-acid vehicle storage batteries.
Electrolytic Capacitor – A capacitor with a negative and a positive terminal that
passes only alternating current. Electrolytics are available in polarized and nonpolarized configurations. Non-polarized (NP) capacitors are useful as inexpensive
crossovers, blocking low frequencies from passing through to mid- or high-frequency speakers. Polarized capacitors have specific positive and negative poles.
This type of capacitor is useful for storing and releasing energy.
Emergency Override – A button or switch, possibly separate or hidden from the
commonly used controls of a security system, that is used specifically to override
or disarm a security system in the event that the primary means is unavailable or
disabled.
EMR Detector – A tool used to find the source of low-frequency tape head interference (electromagnetic radiation, or EMR).
Engine Disable – A means, either electrical or mechanical, of preventing the vehicle’s engine from either starting or running. The most common variety of engine
disable uses a simple automotive relay to inhibit either the starter or the ignition.
Entry Delay – The time interval a security system waits before sounding the
alarm after a vehicle’s door has been opened.
ESN – A phone’s electronic serial number.
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Margin Notes
Exit Delay – The name given to the amount of time a security system waits once
it’s given a command to arm. Exit delays are usually found on non-remote security systems that rely on keypads or the ignition switch to arm. This delay gives
the operator time to exit the vehicle before the system arms.
Farad (F) – The basic unit of capacitance. A capacitor has a capacitance of 1F
when a charge of 1 volt across the capacitor produces a current of 1 ampere
through it. Named after Michael Faraday.
FCC – Federal Communications Commission. The U.S. government agency that
oversees and regulates electronic communications.
Fidelity – A term used to describe the accuracy of recording, reproduction, or
general quality of audio processing.
Flashing Lights – A term used to describe the interfacing of the vehicle’s parking
lights, dome light, emergency lights, etc., with a security system so that the lights
flash by the system.
Flat Response – An output signal in which fundamental frequencies and harmonics are in the same proportion as those of the input signal being amplified. A
flat frequency response would exhibit relatively equal response to all fixed-point
frequencies within a given spectrum.
Fletcher-Munson Curves – A set of curves that depict the uneven frequency
response of human hearing.
FM – See Frequency Modulation.
Free Air Resonance – The frequency at which a speaker will naturally resonate.
Frequency – The term in physics that refers to a number of vibrations or cycles
that occur within a given time.
Frequency Counter – A device that assists in speaker parameter testing, as well
as identifying the frequency of specific tones.
Frequency Modulation (FM) – A method of modulation in which the frequency of the carrier voltage is varied with frequency of the modulating voltage (See
also Amplitude Modulation)
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Frequency Response – A term that describes the relationship between a device’s
input and output with regard to signal frequency and amplitude.
Margin Notes
Fundamental Frequency – The lowest frequency component of a harmonic series.
Fuse – A device designed to provide protection for a given circuit or device by physically opening the circuit. Fuses are rated by their amperage and are designed to
blow or open when the current being drawn through it exceeds its design rating.
Fusible Link – Designed to perform the same task as a fuse, but resembles a wire.
Fusible links are commonly used in ignition switches and other high-current circuits.
GHI
Gain – Refers to the degree of signal amplification.
Generator – A rotating machine that produces DC electricity. Also an electronic
device used for converting DC voltage into AC of a given frequency and wave shape.
Glass Sensor – A device designed to detect the sound of breaking glass or metalto-glass contact, thus triggering a security system. Also called sound sensors,
glass-breaking sensors, or sound discriminators.
Ground – The term given to anything that has an electrical potential of zero. Most
modern vehicles are designed around a negative ground system, with the metal
frame being the vehicle’s ground.
Ground Loop – The term given to the condition that occurs when a voltage
potential exists between two separate ground points.
Harmonic – The overtones and undertones that define the acoustic difference
between two sounds with the same fundamental frequency.
Harness – The universal name for a bundle or loom of wires that compose the
wiring for a system.
Headroom – The difference between the highest level present in an audio signal
and the maximum level an audio device can handle without noticeable distortion.
Hertz (Hz) – The unit of frequency within a specific period, such as alternating
or pulsating current; 1 Hz = 1 cycle per second.
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Margin Notes
High Frequency – Refers to radio frequencies in the 3-30 MHz band. In audio it
usually refers to frequencies in the 5-10 kHz band.
High Pass Filter – A network of components which attenuate all frequencies
below a predetermined frequency selected by the designer. Frequencies above
cut-off are passed without any effect.
Horn (Audio) – Refers to a loading device when part of a bass enclosure, or a
directional device when used with a high-frequency driver or compression driver.
Horn (Security) – Refers to the built-in factory horn in the vehicle. Factory horns
can be of the diaphragm type, voice coil type, or air-pump driven type (air horn).
All types of horns can be interfaced to a security system.
Ignition Kill – A device designed to prevent the vehicle’s ignition circuit from
operating. An ignition kill device can work by either interrupting one or both of
the primary wires leading to the ignition coil or by shorting out (grounding) the
ignition coil’s positive primary wire. Also called Ignition Disable.
Ignition Power – Refers to a source of power in the vehicle, controlled by the
ignition switch, that has +12VDC on it when the ignition key is not in the run and
start positions.
Imaging – The width and definition of a sound stage. Instruments should appear
to be coming from their correct positions, relative to recording.
Impact Sensor – A sensor designated to detect various degrees of impact or vibration applied to the vehicle and then produce an output to trigger a security system.
Impedance (Audio) – A measurement of the resistance to the audio current by
the voice coil of the speaker. (See also Nominal Impedance)
Impedance (Electrical) – The total opposition offered by a device or circuit to
the flow of alternating current (AC).
Inductive Coupling – Radiated noise that is transmitted through a magnetic field
to surrounding lines.
Inductor – An electrical component in which impedance increases as the frequency of the AC decreases. Also known as coils that are used in passive
crossovers. Inductors are rated in Henries.
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Infinite Baffle – A loudspeaker baffle of infinite space that has no openings for
the passage of sound from the front to the back of the speaker. Also, a sealed
enclosure where the internal volume is greater than the Vas of the driver.
Margin Notes
Infrared Sensor – A type of spatial sensor that uses infrared energy to detect an
object (a hand, arm, or body) entering a protected area. (See also Spatial Sensors)
Input (Audio) – The high-level (speaker) or line level (RCA) signal connections
that run into one component from another system component.
Input (Security) – Any wire on a security system designed to accept a signal from
some outside source such as the vehicle’s wiring. Door trigger, hood trigger, trunk
trigger, and sensor trigger wires are all inputs.
Instant Trigger – The term used to describe any trigger input on a security system that is designated to cause the system to respond instantly when triggered.
Integrity – The expected durability of a component or connection.
JKL
Joule – A unit of energy equal to one watt per second.
Jump – To provide a temporary circuit around a component or other circuit.
Keypad – A panel usually made of metal or plastic with numbered push-buttons
(like a touch-tone telephone) designed to provide access to certain types of security or cellular systems.
Kirchoff’s Current Law (KCL) – A law stating that the total current entering a
point or junction in a circuit must equal the sum of the current leaving that point
or junction.
Kirchoff’s Voltage Law (KVL) – A law stating that the voltage supplied to a DC
circuit must equal the sum of the voltage drops within the circuit.
kHz – Abbreviation for kilohertz, or 1000 cycles per second.
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Margin Notes
Last Door Arming – A feature found on some security systems that enables the
system to suspend itself from arming until the last door of the vehicle has been
secured.
LCD – Liquid Crystal Display.
LEDs – Light Emitting Diodes. A form of diode that sheds light. Used in may systems for indicator purposes.
Loudspeaker – An electro-acoustic transducer that converts electrical audio signals at its input to audible sound waves at its output.
Low Frequency – Refers to radio frequencies within the 30 -300 kHz band. In
audio it usually refers to frequencies in the 40-160 Hz band.
Low Pass Filter – A network of components which attenuate all frequencies
above a predetermined frequency selected by the designer. Frequencies below
cut-off are passed without any effect.
MNO
Magnet – A device that can attract or repel pieces of iron or other magnetic material. Speaker magnets provide a stationary magnetic field so that when the coil produces magnetic energy, it is either repelled or attracted by the stationary magnet.
Memory – The word most commonly used to refer to a system’s ability to retain
specific information.
Microprocessor – A semiconductor that can be programmed to perform a variety of tasks in many different systems.
Midrange Driver – A loudspeaker specifically designed to reproduce the frequency in the middle of the audible bandwidth. Most musical energy lies in the
midband.
Milliamps – A unit of measurement of electrical current equal to 1/1000th of an
ampere. The milliampere is the most common unit used when measuring quiescent (minor) current drain.
Module – A term commonly used to describe a self-contained part or device that
can perform a specific function.
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Motion Sensors – A sensor specifically designed to detect a gentle or sharp upand-down or side-to-side motion of the vehicle.
Margin Notes
Multimeter – A common term used to describe a Volt-Ohm-Meter, or VOM. A
multimeter usually can measure volts, ohms, and amperes or milliamperes.
Negative Door Switches – A common type of switch found on most modern
vehicles which provides the trigger for the factory interior lights, key buzzer, factory alarm, etc.
Negative Lead – The lead or line connected to the negative terminal of a current,
voltage, or power source.
Noise Floor – The noise power generated by an audio device in the absence of
any input signal. It is generally measure in decibels.
Nominal Impedance – The minimum impedance a loudspeaker presents to an
amplifier, directly related to the power the speaker can extract from the amplifier.
Normally Closed – Refers to the electrical state in which a switch may rest. Its
contacts are held together or closed so that current is allowed to flow through its
contacts.
Normally Open – Refers to the electrical state in which a switch may rest. Its contacts are held apart or open so that no current flows through its contacts.
Octave – A musical interval between two tones formed when the ratio between
the frequencies of the tone is 2:1.
Ohm – The unit of measurement for electrical resistance.
Ohm’s Law – The statement of the relationship between current, voltage, and resistance. Where I = Current, E = Voltage, and R = Resistance, I=E/R, E=IR, and R=E/I.
Open Circuit – A circuit containing a switch, filament, voice coil, etc., which is
not intact and current cannot flow through.
Oscillator – A device that produces an alternating current or pulsating current or
voltage electronically.
OSHA – Occupational Safety and Health Administration. The U.S. government
agency that regulates workplace safety and health.
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Margin Notes
Output (Audio) – The high-level (speaker) or line-level (RCA) signals sent from
one system component to another, or the high-level signal from an amplifier to
the system speakers.
Output (Security) – Any wire on a security system designed to produce a signal
intended to be wired to some outside circuit or device. Siren wires, flashing light
wires, and door locks are all outputs.
Override Switch – A switch that provides a secondary means to disarm or override a security system in the event the primary means is unavailable. (See also
Emergency Override)
PQR
Pager – A device designed to transmit a signal to the owner of a vehicle in order
to alert him or her that the alarm has been triggered.
Pain Generator(s) – A name given to a type of siren that is specifically designed
to produce a sound of the proper volume and pitch so as to cause physical pain
to a thief’s ears.
Panic – The name given to the feature of a security system that provides the ability to the operator to cause the system’s siren to sound at will. The panic feature
is typically initiated either by pressing a button or buttons on the remote control
transmitter by keypad command, by push button, or by toggle switch.
Parallel Wiring – A circuit in which two or more devices are connected to the
same source of voltage, sharing a common positive and negative point, so that
each device receives the full applied voltage.
Passive Arming – The ability of some security systems to arm without requiring
any direct action from the operator of the vehicle. Passive arming is usually
accomplished when the operator exits the vehicle in the normal fashion. (See also
Last Door Arming)
Passive Crossover – An electrical circuit consisting of capacitors, inductors, and
resistors designed to separate an audio signal into specific speaker groups.
Passive Repeater Antenna – A non-permanently installed, glass-mount antenna
that is without physical connection to the cellular telephone.
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PCS (Cellular) – Personal communications system. Hand-held telephones that
operate in bands of 1900 megahertz and above.
Margin Notes
Peak – An emphasis over a frequency range not greater than one octave.
Period – The amount of time required for a single cycle of a sound wave.
Phase – The timing of a sound wave that is measured in degrees from 0 to 360.
Phase Shift – Frequency interaction in the crossover region of passive crossovers
that can cause some frequencies to be delayed with respect to other frequencies.
Piezo – The name usually given to piezo electric drivers. This type of driver has no
voice coil or magnetic assembly. Instead, piezo electric material expands and contracts when voltage is applied. The material vibrates and either radiates sound directly or drives a diaphragm. They can be used effectively only on high frequencies.
Piezo Sensors – A type of shock or impact sensor that utilizes the properties of
the piezo electric effect inherent in some materials. A piezo sensor typically uses
a piezo electric element to sense impacts or vibrations applied to a vehicle.
Pinswitch – A simple, spring-loaded mechanical switch, used in many different
vehicles, that’s designed to turn on interior lights when doors are opened.
Pinswitches are also used in the installation of most security systems in the hood
or trunk/hatch as a means of triggering the system if such points are opened.
Point of Entry – The term used to describe the doors, hood, trunk/hatch, windows,
sunroof, or any other point through which a thief can gain entry into a vehicle.
Polarity – In electricity, refers to the condition of being either positive or negative.
Polarity Reversal – A DPDT switch connected between a pair of DC input terminals so that the polarity of a pair of output terminals can be reversed or
switched.
Portable Cellular Telephone – A hand-held cellular telephone designed to operate as a self-contained unit. Portable cellular telephones are restricted to 0.6 watts.
Positive Lead – The lead or line connected to the positive terminal of a current,
voltage, or power source.
Potentiometer – A variable resistor made with either carbon or wire wound material that attenuates a signal.
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Margin Notes
Power – The amount of energy (in joules) that a device delivers or consumes
divided by the time (in seconds) that the device is operating.
Power Door Locks – The feature where door locking and unlocking is performed
by some mechanical means other than human power. Power door locks may be
electric, vacuum, or a combination of the two.
Power Line Noise – A varying AC ripple that is found riding on a DC voltage. It
is recognized by a whining that varies with engine speed.
Power Windows – The feature where the opening and closing of the vehicle’s
windows is performed by some mechanical means other than human power.
Power windows are typically operated by electric motors.
Pre-amp – A circuit unit that takes a small signal and amplifies it sufficiently to
be fed into the power amplifier for further amplification. A pre-amp includes all
of the controls for regulating tone, volume, and channel balance.
Programming Adapter – A device used for programming cellular telephones that
allows the telephone to be programmed only when the device is attached.
Proximity Sensor – A common term for a spatial-type sensor that can be either
the radar, ultrasonic, or infrared type. (See also Spatial Sensor)
Pulsed Output – An output of a security system usually used to flash parking
lights or honk horns; it is pulsed or turned on and off by the security system.
Quiescent Current – A term that describes the amount of current consumed by
a circuit when it is not performing any work (sometimes referred to as standby
current).
Qtc – Measurement of a speaker and enclosure working together as one.
Qts – The measurement of the speaker as a motor, taking into consideration all
mechanical and electrical losses.
Radar Sensor – A common name for a type of spatial sensor.
Range (Audio) – Usually described as frequency range, this is a system’s frequency transmission limit, beyond which the frequency is attenuated below a
specified tolerance. Also, the frequency band or bands within which a receiver or
component is designed to operate.
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Range (Security) – The term used to quantify the maximum operating distance
that can exist between a vehicle and the remote control transmitter. Range is usually expressed in feet or yards.
Margin Notes
Rarefaction – A state or region of minimum pressure in a medium traversed by
compression waves (sound waves).
Real-Time Analyzer (RTA) – A spectrum analyzer that measures an audio signal
while it is being reproduced.
Receiver – A device designed to receive a signal or command from a source such
as a transmitter.
Relay – An electromagnet switch that allows small, relatively low-level signals to
operate higher amperage devices. Also used when polarity reversal is necessary.
Remote – A common name for the remote control unit transmitter used with a
remote security system.
Remote Start – The feature where a security system or accessory module allows
the vehicle operator to start the engine using a remote transmitter without actually being inside the vehicle.
Reset – The ability of a security system to automatically stop sounding the siren
and return to an armed state after being triggered, as long as no further trigger
conditions are present.
Resistance – The electrical term used to describe the property that various materials possess to restrict or inhibit the flow of electricity. Electrical resistance is relatively low in most metals and relatively high in most nonmetallic substances.
Electrical resistance is measure in ohms.
Resonance – The term used to describe the tendency of objects to vibrate at certain
frequencies. This can be a useful or undesirable effect, as in planned enclosure or
driver resonance, or as in unplanned enclosure resonance or wall resonance.
Retriggering – See Alarm Retriggering.
RF – Radio Frequency. An AC frequency that is higher than the highest audio frequency.
Ripple – The deviation from a flat response in the passband.
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Margin Notes
RMS – Root Mean Square.
Roll-Off – Relates to the attenuation of frequencies, above or below a given point,
at a specific rate.
Roof-Mount Antenna – A permanently-installed antenna located in the center of
the vehicle’s roof.
STU
Scanning – The popular term given to the way a thief breaks into a remote security system by quickly and sequentially transmitting all the possible security codes
of a victim’s security system.
Seat Sensor – A pressure-activated switch designed specifically for use in detecting any pressure applied to vehicle’s seat.
Sensitivity – The rating of a loudspeaker that indicates the level of sound intensity the speaker produces (in dB) at a distance of one meter when it receives one
watt of input power.
Sensor – A device designed to detect or sense an intrusion or attack upon a vehicle by monitoring such things as motion, vibration, impact, sound, or the presence of a foreign mass.
Sensor Bypass – The ability of a security system to automatically or manually
delete or bypass the triggers from all or some of the sensors tied into the security
system.
Shock Sensor – A sensor that is specifically designed to detect a shock or impact
applied to the vehicle.
Short Circuit – The condition that occurs when a circuit path is created between
the positive and negative poles of a battery, power supply, or circuit. A short circuit will bypass any resistance in a circuit and cause it not to operate.
Signal-to-Noise Ratio – The s/n ratio indicates how much audio signal there is in
relation to noise, or a specified noise floor.
Siren – Any kind of device, mechanical or electronic, that is designed to produce
a loud warning sound when triggered by a security system.
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Sound – A type of physical kinetic energy called acoustical energy. (See also
Acoustical Energy)
Margin Notes
Sound Discriminator – A device designed to listen to, evaluate, and discriminate
between the sounds that may be heard within the interior of a vehicle, and then
trigger the security system if the sound fits within the parameters of what the sensor is designated to react to.
Sound Pressure Level (SPL) – An acoustic measurement for the ratios of sound
energy. Rated in decibels (SPL, dBA, SPL dBC).
Sound Waves – Fluctuating waves of pressure that travel through a physical medium such as air. An acoustic wave consists of a traveling vibration of alternate compressions and rarefactions, whereby sound is transmitted through air or other media.
Spatial Sensors – Devices specifically designed to detect intrusions into or
around the vehicle by monitoring the space in and around the vehicle for intruders. These sensors work on a variety of different principles, including ultrasonics,
radar, radio frequency, and infrared.
SPDT – Single Pole Double Throw. A relay that has only one pole or contact but
whose contact can throw or make electrical contact with two separate stationary
contacts. This is the most commonly used relay in the mobile electronics industry.
Spider – A flat, round, springy device that holds the vibrating cone of a dynamic loudspeaker. The spider is where the diaphragm meets the voice coil.
SPST – Single Pole Single Throw. A relay that has only one pole or contact and
can only throw or make electrical contact with one stationary contact.
Staging – The accuracy with which an audio system conveys audible information
about the size, shape, and acoustical characteristics of the original recording space
and the placement of the artists within it.
Starter Disable – Any circuit or device used alone or in conjunction with a security system that is designed to prevent the vehicle’s starter from operating.
Status – The state a system is in at any given time.
Subwoofer – A loudspeaker made specifically to reproduce frequencies below
125 Hz.
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Margin Notes
Switch – A switch is any form of mechanical, electronic, electromechanical, magnetic, or mercury device that either opens or closes a circuit.
Switch Sensing – Refers to the inputs on a security system designed to detect a
switch closure from such triggers as a door, hood, or trunk/hatch pinswitches.
System Reset – See Reset and Alarm Reset.
TDMA (Cellular) – Time division multiple access. A digital communications
scheme used in some switching systems.
Total Harmonic Distortion (THD) – Given as a percentage, a measurement of
how much a device may distort a signal. Figures below 0.1% are considered to be
inaudible.
Transceiver – A combination radio transmitter/receiver usually installed in a single housing and sharing some components.
Transducer – Any device that converts energy from one form to another, e.g.,
electrical to acoustic or vice versa. Loudspeakers and microphones are two types
of transducers.
Transfer Function – The change in the low end of a low frequency system
brought on by loading the device into the cabin of a vehicle.
Transistor – An active (commonly three-terminal) solid-state device in which a
larger output current is obtained by small changes in the input current.
Transmitter – The name given to the hand-held remote control unit used by a
vehicle operator to arm/disarm and perform accessory functions on a vehicle
security system. More commonly called a remote.
Transportable Cellular Phone – A three-watt mobile telephone combined with
a high-capacity 12-volt battery and portable antenna.
Trigger – The common name for any type of stimulus that will cause a security
system to produce an alarm. A trigger could come from a pinswitch, a sensor, or
a direct command from a transmitter or accessory button.
Trunk Lines – The way the cellular system transfers the mobile calls to the landline network.
196
THE BASIC INSTALLER STUDY GUIDE
GLOSSARY OF TERMS
Trunk Release – The ability of a system to release the latch of the trunk/hatch by
remote control.
Margin Notes
Tweeter – A small loudspeaker or driver meant to reproduce high frequencies.
Ultrasonic Sensor – A form of spatial sensor that is designed to detect an intrusion
into a vehicle by monitoring the space within the vehicle with ultrasonic energy.
Unfused Wire – Any section of wire between the power supply and a load that
does not include the protection of a fuse or circuit breaker.
VWXYZ
Valet – A word used to describe the state in which a security system may be
placed in which it would be prevented form arming passively and/or actively.
Valet Switch – The switch designed to provide the control to place the security
system into or bring the system out of the valet state.
Vas – Compliance. A measurement in liters or cubic feet of the volume of air that
is equal to the compliance of the speaker’s total suspension.
Voice Coil – A coil of wire that takes in the electrical energy coming from the
amplifier and converts it into acoustic energy or mechanical motion.
Volt – The term used to refer to the property of electrical pressure through a circuit.
Voltage – The electrical pressure produced to do work.
Voltage Drop – The amount of energy consumed when a device has resistance in
its circuit. The voltage (E) measured across a resistance (R) carrying a current (I).
E=IR. (See also Volt)
Voltage Sensing – A name given to a form of alarm system trigger that relies on
sensing a change in the voltage of the vehicle.
VOM – Volt-Ohm-Meter, sometimes called a Volt-Ohm-Millimeter. A multimeter
that measures voltage, ohms, and milliamperes.
GLOSSARY OF TERMS
THE BASIC INSTALLER STUDY GUIDE
197
Margin Notes
Watt – The basic practical unit of measure for electrical or acoustical power.
Wattage – Electrical power.
Wave – A single oscillation in matter (e.g., a sound wave). Waves move outward
from a point of disturbance, propagate through a medium, and grow weaker as
they travel farther. Wave motion is associated with mechanical vibration, sound,
heat, light, etc.
Waveform – The shape of a wave.
Wavelength – The length of distance a single cycle or complete sound wave travels.
Window Roll-up – The term used for the feature that causes the window(s) on a
vehicle to close upon arming, or open and close as part of a convenience feature
of a security system.
Woofer – A large dynamic loudspeaker that is well suited for reproducing bass
frequencies.
Xmax – The distance a speaker cone can travel before that magnet loses control
over the voice coil.
Zero Output – The absence of output signal or output power.
Zone – The specific area of the security system’s coverage, or a term used to
describe a specific trigger input.
198
THE BASIC INSTALLER STUDY GUIDE
GLOSSARY OF TERMS
APPENDIX
Margin Notes
NOISE EXPOSURE CHART
Sound Level (dBA)
Maximum 24-Hour Exposure
Occupational
Nonoccupational
80
85
90
95
100
105
110
115
120
■
8 hr.
4 hr.
2 hr.
1 hr.
30 min.
15 min.
0 min.
Figure A-1. Noise Expousure Chart.
2
E
R
2
E
R
I •R
I•E
P•R
P
I
200
P
E
P I
P/R
E R
E
I
2
IR
•
P = Watts
I = Amps
■
4 hr.
2 hr.
1 hr.
30 min.
15 min.
8 min.
4 min.
2 min.
0 min.
P
2
I
E
P
E = Volts
R = Resistance
Figure A-2. OHM’s Law.
THE BASIC INSTALLER STUDY GUIDE
APPENDIX
Margin Notes
■
Figure A-3. Electronic Symbols.
APPENDIX
THE BASIC INSTALLER STUDY GUIDE
201
Margin Notes
202
THE BASIC INSTALLER STUDY GUIDE
APPENDIX
MAGNUSON-MOSS ACT
Margin Notes
Have either of these situations happened to you? A customer wants to purchase
an aftermarket accessory for his new car, but is concerned because the car dealer
has told him that any accessory (i.e. car alarm, CD player, etc.) not purchased and
installed by the dealer will void the car’s warranty?
Or the customer has purchased an aftermarket accessory and then returns to your
store because the dealer has refused to perform warranty work based on the fact
that the customer purchased your product, which had nothing to do with the
problem the customer is now experiencing?
It is important for retailers to know their rights under the antitrust laws so they
can assure their customers that any such purchase will in no way affect the warranty on their cars.
IT IS A VIOLATION OF FEDERAL ANTITRUST LAWS—
1
For a manufacturer (or its authorized representative) to condition a warranty
on the purchase and use of its own parts or service.
2
For a manufacturer (or its authorized representative) to refuse to honor a
warranty unless the manufacturer can show that an aftermarket accessory is the
cause of a particular malfunction otherwise covered by the warranty.
KNOW YOUR RIGHTS
For more information, contact Federal Trade Commission at (202) 326-2222 or
write to the Consumer Electronics Association - Mobile Electronics Division, 2500
Wilson Boulevard, Arlington, Virginia 22201-3834.
APPENDIX
THE BASIC INSTALLER STUDY GUIDE
203
INSTALLER CHECKOUT SHEET
Customer Name: _______________________________
Phone#: _______________
Vehicle Year: __________________________________
Tag#: _________________
Make: _________________________________
Inspected: Y____ N____
Model: _________________________________
Color: _________________________________
Date: ________________
SYSTEMS
WORKING
Yes
No
Horn
Turn Signal
Flashers
Headlights
Dashlights
Cig Lighter
Clock
Wipers
Rear Defroster
Fan/Heater/AC
Sun Roof
Plate Lights
Elec Windows
Elec Door Lock
Elec Seats
Elec Mirrors
Elec Sunroof
Speedometer
____
____
____
____
____
____
____
____
____
____
____
____
____
____
____
____
____
____
WORKING
Yes
No
____
____
____
____
____
____
____
____
____
____
____
____
____
____
____
____
____
____
Domelight
Power doorlocks
Gauges
Brake Lights
Back-up Lights
Power Antenna
_____________
_____________
____
____
____
____
____
____
____
____
____
____
____
____
____
____
____
____
Comments on Interior: ____________________________________________________
______________________________________________________________________
Comments on Exterior: ____________________________________________________
______________________________________________________________________
Comments on Battery & Cables: ____________________________________________
Installer: ________________________
204
Date: ______________
THE BASIC INSTALLER STUDY GUIDE
Time: _________
APPENDIX
NOISE PROBLEM CHECKLIST
Invoice #: ________________________________
Date: ____________________
Customer Name: _______________________________________________________
Car Yr/Model: __________________________________________________________
Installer Name: _________________________________________________________
Equipment Installed:_____________________________________________________
_____________________________________________________________________
_____________________________________________________________________
EQUIPMENT PERFORMANCE
Rate 1 Thru 5
(1 = Noise Free 5 = Extremely Noisy)
AM Section
FM Section
Tape Section
Compact Disc
CR02 Bias
Low Bias
____
____
____
____
____
____
Balance
Scan
Clock
AM MPX Section
FM MPX Section
Dolby B Section
NOISE TYPES
Ignition
____
Wiper Motor
____
Horn Relay
____
Window Defogger ____
ENTRY POINTS
Antenna
+12VDC
+12VDC Clock Lead
Antenna Lead
Case Radiated
Internal Noise
____
____
____
____
____
____
____
____
____
____
____
____
Air Conditioning
Electric Windows
Alternator
Power Windows
Type
Type
Type
Type
Type
Type
of
of
of
of
of
of
Noise
Noise
Noise
Noise
Noise
Noise
____
____
____
____
Fader
____
Seek
____
Memory ____
Blinker
Instrument Gauges
Computer Clock
Power Seats
_________________________
_________________________
_________________________
_________________________
_________________________
_________________________
COMPONENT AFFECTED
Deck
____
Compact Disc
____
Crossover ____
Equalizer
____
Amplifier ____
Powered Speakers ____
SOLUTIONS
Changed Ground
____
Removed Grounds ____
New 12VDC Source ____
Radiator
____
____
____
____
____
In-Line Suppressor(s) ____
Braided Cable Grounds ____
Antenna Isolator
____
FM Signal
____
Alarm System ____
Grnd Loop Isolated ____
New Power Supply ____
Secondary Noise
Suppressor(s)
____
COMMENTS: ____________________________________________________________
________________________________________________________________________
Signed____________________________________________
Date: ______________
APPENDIX
THE BASIC INSTALLER STUDY GUIDE
205
REFERENCE MATERIALS
Margin Notes
Alternator Whine, David Navone, Navone Engineering, 4119 Coronado, Suite #4,
Stockton, CA 95204; Autosound Technology 2000, (919) 570-0341.
Audio Control Technical Papers 101, 102, 103, Richard Chinn, Audio Control,
Lynwood, WA.
Autosound Technology 2000, Tech Briefs, 2112 Westover Terrace, Burlington, NC
27215; (919) 570-0341.
Basic Electricity and DC Circuits, Ralph Olivia and Charles Dale, Texas Instruments,
1979.
Beat the Book with Fluke Meters, John Fluke Manufacturing Company, 1987,
Everett, WA.
Buchsbaum’s Complete Handbook of Practical Electrical Reference Data, Second Edition,
W. Buchsbaum, Prentice Hall, 1982.
Building Speaker Systems, G. McComb, Master Publishing, Inc., 1988.
Cellular Installation Handbook, Revised Edition, Bishop and Associates, 22121
17th Ave., S.E., Bothell, WA 98021.
Cellular Mobile Radio Telephones, S. Gibson, Prentice Hall, 1987.
Cellular Telephone Installation Handbook, Michael Losee, Quantum Publishing, 1988,
Mendocino, CA 95460.
Handbook of Electronic Tables and Formulas, Sixth Edition, Howard W. Sams
Engineering Staff, Howard W. Sams and Company, 1988.
High Performance Loudspeakers, Third Edition, Martin Colloms, Pentech Press, 1985.
How to Design and Build Audio Amplifiers, Second Edition, M. Horowitz, Tab Books
Inc., 1980.
Loudspeaker Design Cookbook, Vance Dickason; Old Colony Sound Lab,
(603) 924-6371.
206
THE BASIC INSTALLER STUDY GUIDE
REFERENCE MATERIALS
Loudspeaker and Headphone Handbook, John Borwick, Butterworth and Company, 1988.
Margin Notes
Musical Acoustics, D. Hall, Wadsworth Inc., 1980.
Noise Control – OSHA, Department of Industrial Relations, State of California
#S680, 1986.
Sound Reinforcement Handbook, Gary Davis and Ralph Jones, 1988, Hal Leonard
Publishing, 7777 W. Bluemound Road, Milwaukee, WI 53213.
REFERENCE MATERIALS
THE BASIC INSTALLER STUDY GUIDE
207
Index
INDEX
INDEX
ABC
Accessories ......................................................................28, 76, 84, 90, 99, 110
Accessory Output Devices......................................................................145, 152
Acid..................................................................................................68, 117, 183
Air Horns ................................................................................................63, 176
Air Pump........................................................................................................176
Alarm ..............................................33, 64-65, 72, 88, 100, 123-124, 134, 148,
............................................176, 181, 183, 189-190, 193, 196-197, 203, 205
Alarm System ..........................................................64, 123, 176, 181, 197, 205
Alternating Current..................26-27, 67, 75, 80, 130, 176-177, 183, 186, 189
Alternator Whine ....................................55, 78, 88-89, 97, 123, 125, 176, 206
Alternator ................................27, 29, 32, 50, 55-56, 67, 75, 77-78, 80, 88-89,
......................................97, 100, 102-103, 108, 122-123, 125, 176, 205-206
American Wire Gauge ..........................................................................36, 91-92
Ammeter ........................................................................................100, 103, 176
Amperage ..................................................36-37, 51, 54, 64, 69-70, 75, 78, 95,
....................................................98, 103, 105-108, 123, 126, 176, 185, 193
Ampere ....................................................................................35, 177, 184, 188
Amplifier ................29, 32, 34, 36-38, 44, 47, 49-50, 56-59, 69-70, 72, 77-81,
........ 89, 91, 94, 98, 114, 121, 123, 146, 178, 180, 189-190, 192, 197, 205
Amplitude ..........................................26-27, 131, 133, 137-140, 177, 184-185
Analog Meters ................................................................................................108
Analog Switch ................................................................................................177
Anode ................................................................................................72-73, 177
Antenna ..................................85-86, 89, 94, 98, 120, 122, 153, 157-162, 164,
............................166, 170, 172-173, 177, 179-181, 190, 194, 196, 204-205
Arm................................46, 116, 145, 152, 177, 179, 182, 184, 187, 190, 196
Audio ..........................................................26-27, 32, 35-36, 41, 46-47, 55-56,
..............59-60, 70, 75, 78-79, 89, 91, 97-99, 109, 121, 123, 125, 130, 132,
....139, 142-143, 162, 165, 167, 171, 177-178, 181, 184-190, 192-195, 206
Audio Signal............27, 46-47, 60, 79, 130, 142, 171, 177, 185, 190, 193-194
Audio System........................................................26, 32, 55-56, 75, 78, 89, 91,
.................................................... 97, 99, 109, 121, 123, 125, 165, 167, 195
Autosound Systems ..........................................................................................88
210
THE BASIC INSTALLER STUDY GUIDE
INDEX
Bandpass ............................................................................................62, 81, 178
Bandpass Filter ..................................................................................62, 81, 178
Bass Reflex......................................................................................................178
Battery ..........................27-28, 36, 41, 43, 51-52, 55-58, 67-70, 72-73, 75-78,
................................86-88, 90-91, 95, 99-104, 108, 111, 117-118, 120-125,
....................................................154-157, 167, 173, 178-179, 194, 196, 204
Bookkeeping ....................................................................................................85
BOSCH ..............................................................................................63-65, 114
Bridging..........................................................................................................178
Cable ......................36-38, 42, 44, 58, 62, 68-70, 77-78, 81, 87-89, 91, 94-95,
..........98-99, 101-102, 118, 121-123, 157-159, 162, 166-168, 172-173, 205
Capacitance Glass Tester ................................................................................160
Capacitor ................................48-50, 60-61, 67, 79, 81, 99, 171, 179, 183-184
Cathode ......................................................................................72-74, 177, 179
Cell ..........................................................................................68, 122, 178-179
Cellular ....................................................................41, 153, 156-158, 161-162,
..........................................................167, 172, 179, 187, 190-192, 196, 206
Cellular System ......................................................................................179, 196
Cellular Telephone..........................................156-157, 161, 179, 190-191, 206
Channels ..................................................................................................34, 178
Chassis ........................52, 55, 69, 72, 89-90, 98, 106, 121, 157, 168-169, 179
Chirp......................................................................................................146, 179
Circuit........................................27, 29-31, 33-35, 38-45, 47-48, 51-52, 54-55,
..........57-58, 60, 62, 64-66, 68, 72-73, 77, 80-81, 91, 95-96, 100-101, 107,
120, 142, 148, 151, 155, 176-177, 179-183, 185-187, 189-190, 192, 194-197
Cleaning............................................................................................91, 118-119
Clipping ............................................................................8-59, 78-79, 143, 180
Closed Circuit ................................................................................................180
Coil ......................................38, 42, 50, 58-59, 61-66, 98, 107, 109, 152, 159,
..................................176, 178, 180, 182, 186, 188-189, 191, 195, 197-198
Co-linear Antenna ..........................................................................................180
Compliance ............................................................................................180, 197
Conductors ................................................................................37, 48, 159, 179
Connections ..............................................................43, 53, 57, 71, 90, 92, 97,
..................................................................102, 122, 125, 144, 155, 168, 187
Constant Output ............................................................................................180
Contacts ................................46, 62-66, 95, 147, 152, 154, 171, 182, 189, 195
Control Unit ..........................................................145, 158, 178-180, 193, 196
Coulomb ..................................................................................................35, 180
INDEX
THE BASIC INSTALLER STUDY GUIDE
211
Coupling................................................................................158, 160, 182, 186
Coupling Box ........................................................................................158, 160
Crimping..........................................................................93, 111, 118, 158-159
Crossover ............................................39, 44, 47, 49-50, 56, 59-62, 79, 81, 89,
........................................................ 97-98, 114, 123, 180-181, 190-191, 205
Current ................................26-36, 38-45, 47-48, 51-52, 54-58, 62-64, 67-69,
....................................71-75, 77-78, 80-81, 91-92, 100-103, 105-109, 111,
............................123, 130, 153, 157, 163-164, 176-189, 191-192, 196-197
Current Draw ........................................................................100-101, 103, 157
Current-fed Antenna ......................................................................................181
Cutting............................................................................................112-115, 118
DEF
Damping ........................................................................................................181
Decibel ..........................................................................................116, 133, 181
Dedicated Fuse ..............................................................................................181
Defogger Lines................................................................................................160
Destructive Interference ........................................................136, 138, 171, 181
Diaphragm ............................................................130, 176, 181, 186, 191, 195
Difference of Potential ........................................................................29-31, 182
Digital ........................................................45, 60, 103-104, 108-110, 125-126,
............................................................155, 157, 168-170, 179, 181-183, 196
Digital Audiotape (DAT) ................................................................................181
Digital Multimeter ....................45, 103-104, 110, 125-126, 155, 168-169, 182
DIN ................................................................................................................182
Diode....................................................65, 72-74, 152-153, 171, 177, 182, 188
Direct Current..............................27-28, 48, 67-68, 75, 80, 106, 108, 178, 181
Disassembly......................................................................................................86
Dome Light....................................................................................101, 182, 184
Door Lock ..............................................................................................182, 204
Drills ..............................................................................................................112
Driver ........................................................60, 65, 110, 141, 153-154, 161-165,
..................................................167, 176, 180, 182, 186-188, 191, 193, 197
Dynamic Range ..............................................................................143-144, 183
212
THE BASIC INSTALLER STUDY GUIDE
INDEX
Effective Resistance ....................................................................................34, 77
Efficiency ......................................................................................102, 116, 183
Electrical Laws............................................................................................26, 43
Electrical Systems ............................................................................................97
Electrolyte ........................................................................................68, 102, 183
Electrolytic Capacitor ....................................................................................183
Electronic Components ....................................................................................27
Electronic Serial Number ..............................................................................183
Emergency Override ..............................................................................183, 190
EMR Detector ........................................................................................114, 183
Enclosure..................................................85, 111, 120, 178, 186-187, 192-193
Engine Disable........................................................................145, 150-151, 183
False Alarms ..........................................................................................148, 154
FARAD ............................................................................................49, 179, 184
Field Disturbance Sensor................................................................................150
Filter ............50, 55, 60, 62, 68, 81, 98-100, 121-122, 148, 178-179, 186, 188
Fire ..................................................................................44, 118-119, 124, 126
Fire Extinguishers ..........................................................................................118
First Aid ................................................................................................119, 124
Flashing Lights ..............................................................................................184
Flat Response..........................................................................138-141, 184, 193
Fletcher-Munson Curves, 140, 184
FM ....................................................................94, 97, 160, 162, 172, 184, 205
Frequency............................26-27, 47-50, 55-56, 60, 62, 79, 94, 97, 114, 122,
............................................130-133, 138-141, 148-149, 151-152, 160-161,
............................................171, 176-181, 183-186, 188, 191-193, 195-196
Frequency Counter ........................................................................................184
Frequency Response ......................................................138-141, 178, 184-185
Fundamental Frequency ........................................................................141, 185
Fuse ............................................34, 51-52, 57-58, 77-78, 88, 91, 95, 99, 101,
..........................................103, 106, 121, 123, 126, 157, 179, 181, 185, 197
Fusible Link ..................................................................................................185
Fusing ..................................................................................................57, 88, 95
INDEX
THE BASIC INSTALLER STUDY GUIDE
213
GHI
Gauges................................................................................37, 91, 155, 204-205
Glass................................138-139, 147-148, 152, 158-160, 166, 172-173, 185
Glass-Mount Antenna ....................................................................159-160, 190
Graphic Equalizer ..........................................................................................140
Ground ..........................................................26, 43, 52, 55-56, 58, 60, 65, 69,
......................................77-78, 87, 89-91, 93-95, 97-99, 102, 106, 109, 121,
..................123, 125, 153, 155, 157, 161, 167-169, 172, 176, 181, 185, 205
Ground Loop ........................................55-56, 78, 89-90, 97-98, 121, 123, 185
Ground Paths ..................................................................................................89
Ground Potential ........................................................................................89-90
Hand Nibbler ................................................................................................114
Handset ..........................................................................................................157
Harmonic ......................................................................................141, 185, 196
Head AMP ......................................................................................................114
Headroom ......................................................................................143-144, 185
Hearing Protection..........................................................................................116
Henries ....................................................................................................47, 186
Hertz................................................................................27, 131, 149, 176, 185
Horns ......................................................................................63, 176, 186, 192
Human Hearing ............................................................132-133, 138, 140, 184
Hydrometer ....................................................................................102-103, 126
IASCA ............................................................................................37-38, 58, 69
Ignition Disables ............................................................................................150
Ignition Lead ............................................................................................88, 157
Ignition Power................................................................................................186
Ignition Switch Functions ................................................................................76
Impact Sensor ................................................................................172, 186, 191
Impedance ..................................................................41, 56, 68, 159, 186, 189
Inductive Coupling ........................................................................................186
Inductor ....................................................................47, 50, 60-61, 79, 81, 186
Infinite Baffle ..................................................................................................187
Infrared Sensor ..............................................................................................187
214
THE BASIC INSTALLER STUDY GUIDE
INDEX
Installation ..........................29, 32, 38, 63, 68, 72, 81, 83-126, 130, 144, 152,
....................................154-156, 158, 161-162, 165, 167, 169-170, 191, 206
Interface ................................................................................................153, 165
JKL
Joule ..................................................................................................35, 80, 187
Jump Starting ................................................................................................157
Landline ........................................................................................................196
Lead Dress ........................................................................................................87
Leads......................................................46, 58, 71-72, 85, 87-89, 94, 100-101,
....................................105-106, 108-109, 114, 120-121, 123, 125, 137, 182
Load Testing ..................................................................................................102
Loudspeaker ............................................60, 134-135, 180, 182-183, 187-189,
............................................................................194-195, 197-198, 206-207
MNO
Magnet ..........................................................................110, 119, 147, 188, 198
Memory..................................................................................................188, 205
Meters....................................................................................103, 105, 108, 206
MicroFarads......................................................................................................49
Microphone ..................................................130, 148, 158, 161-163, 172, 196
Mobile Telephone ..........................................................................................196
Module ..................................................................................................188, 193
Motion Sensor........................................................................................147, 189
Negative Lead ................................................................................105-106, 189
Noise ..........................................48, 50, 55-56, 60, 68, 72, 87-91, 94, 96-100,
..........................104, 106, 109, 114, 116-117, 120-123, 125, 139, 141-144,
..................155, 158, 171-172, 176, 182, 186, 189, 192, 194, 200, 205, 207
Noise Sniffers..................................................................................................109
Nominal Impedance ..............................................................................186, 189
INDEX
THE BASIC INSTALLER STUDY GUIDE
215
Normally Closed ........................................................................64-66, 147, 189
Normally Open ..........................................................................64-66, 147, 189
Occupational Safety and Health Administration............................116, 126, 189
Octave ............................................................................61, 141, 171, 189, 191
OEM ..............................................................................................65, 75, 77-78
Ohm ..........................................................28-36, 38, 40-42, 44, 51, 54-55, 69,
..................................................77-78, 80, 105, 107, 155, 176-177, 189, 200
Ohm's Law ....................................28-36, 38, 42, 54, 69, 77, 80, 176, 189, 200
Open Circuit................................................................................48, 58, 68, 189
Oscillator ......................................................................................146, 177, 189
Oscilloscope ..........................................................27-28, 59, 97, 111, 168, 180
PQR
Pager ..............................................................................................................190
Parallel Wiring..........................................................................................42, 190
Passive Crossover ..........................................44, 47, 49-50, 60-61, 79, 81, 190
Passive Repeater Antenna ..............................................................................190
Period..........................................34, 80, 93, 131-132, 150, 153, 176, 185, 191
Phase ......................................75, 86-87, 97, 134-138, 154, 171, 180-181, 191
Phase Shift..............................................................................................135, 191
Pinswitch................................................................................146-147, 191, 196
Polarized Capacitors ......................................................................................183
Portable Cellular Telephone ..........................................................................191
Positive Lead ..................................................................................105-106, 191
Potentiometer ..................................................................................46, 171, 191
Power ............................26-29, 31-32, 34-38, 41-44, 47, 49-54, 56-60, 62-64,
....................67-70, 74-81, 85, 87-89, 91, 94-95, 98-99, 101, 106, 110-111,
............113-114, 116-117, 119-122, 125, 133, 143, 146, 152-153, 155-157,
160-161, 168, 176, 178-181, 183, 186, 189, 191-192, 194, 197-198, 204-205
Power Cable ............................37, 42, 58, 69, 77, 88, 95, 98-99, 121-122, 157
Power Handling................................................................................................51
Power Line Noise ..........................................................................................192
Power Rating ..............................................................................................51, 78
Power Window ............................................................52-53, 63, 152, 192, 205
216
THE BASIC INSTALLER STUDY GUIDE
INDEX
Power Wiring ......................................................................................76, 78, 91
Programming ................................................................................157, 162, 192
Pulsed Output........................................................................................172, 192
Margin Notes
QTC ..............................................................................................................192
Radar........................................................................28, 149-150, 182, 192, 195
Radar Detectors ................................................................................................28
Radar Sensor ..................................................................................150, 182, 192
Radiated Noise..........................................................87-88, 94, 97-99, 122, 186
Radio Frequency Transmitters........................................................................151
Radio Frequency ................................94, 97, 122, 151-152, 160-161, 193, 195
Range ....................................56, 62, 101, 103-109, 126, 132-133, 138, 141, 1
..............................43-144, 149, 152, 154, 168-169, 178, 180, 183, 191-193
Rarefaction..............................................................................134-135, 181, 193
Reassembly ......................................................................................................86
Receiver ..................................................149, 156, 163-164, 173, 192-193, 196
Reception Problems........................................................................................166
Relay......................................................................................62-66, 71, 81, 106,
..........................................................152, 156, 171, 182-183, 193, 195, 205
Remote ............................................................ 87, 94, 145, 151-153, 162, 165,
............................................................176, 179-180, 190, 193-194, 196-197
Remote Control ............................145, 151, 162, 165, 179, 190, 193, 196-197
Remote Control Transmitter ..................................................151, 179, 190, 193
Resistance ............................28-35, 37-41, 44-47, 52, 54-57, 63, 68-70, 72-73,
........77, 80-81, 90-91, 93, 105, 107, 123, 177-178, 186, 189, 193-194, 197
Resistors ....................................................35, 39-42, 44-45, 60, 74, 77-78, 190
Resonance ..............................................................138-139, 171, 181, 184, 193
Response ................................138-141, 146, 153-154, 162, 178, 184-185, 193
Retriggering ....................................................................................................193
Ripple ..............................................55-56, 67-68, 100, 122, 178-179, 192-193
INDEX
THE BASIC INSTALLER STUDY GUIDE
217
Margin Notes
STU
Safety ..................................13-16, 83, 100, 105, 113, 115-118, 126, 153, 189
Saws................................................................................................112-113, 116
Seat Sensor ....................................................................................................194
Security ..........................................................................28, 41, 46, 63, 76, 106,
....................................................126, 129-173, 176-180, 182-188, 190-198
Security System ........................................................63, 76, 106, 126, 144-146,
............................................151-156, 172, 176-180, 182-187, 190, 192-198
Semiconductors ..........................................................................................71-72
Sensitivity ..........................................................................44, 46, 107, 148, 194
Sensors ....................63, 145, 147-150, 164, 168, 185, 187, 189, 191, 194-195
Shock Sensor..........................................................................................148, 194
Short Circuit ..........................................................57-58, 77, 96, 107, 179, 194
Signal-to-Noise ..............................................................................................194
Single Pole Double Throw ..............................................................65, 152, 195
Single Pole Single Throw ......................................................................152, 195
Sirens ......................................................................................63, 146, 156, 180
Slope ........................................................................................................61, 179
Solder ........................................................................92-93, 110, 117, 122, 144
Sound ......................................35, 49, 56, 79-81, 116, 126, 129-135, 137-141,
............................................143-144, 146, 148-149, 171, 176-178, 181-183,
............................................185-188, 190-191, 193-195, 198, 200, 206-207
Sound Discriminator ..............................................................................148, 195
Sound Pressure Level ............................................................................133, 195
Sound Wave ..................130-132, 134, 149, 171, 176-178, 191, 193, 195, 198
Sources ......................................................................................87, 98, 134, 155
Spatial Sensors........................................................................149-150, 187, 195
Speaker ..........38, 41-42, 44, 47, 57-58, 60, 69-70, 77-79, 81, 85, 87-88, 104,
..................106-107, 111, 113-115, 120-121, 123, 125, 130, 135-139, 141,
..........146, 158, 161, 165, 180-182, 184, 186-190, 192, 194, 197-198, 206
Spider ............................................................................................................195
Staging............................................................................................................195
Starter Disable ........................................................................................150, 195
Starter Interrupt..............................................................................................151
Stiffening Capacitor ..........................................................................................50
Subwoofer ..........................................................................42, 47, 79, 142, 195
Sulfuric Acid ....................................................................................68, 117, 183
218
THE BASIC INSTALLER STUDY GUIDE
INDEX
Switch ........................41, 52, 58, 62-64, 71, 74, 76, 79, 88, 91, 105-107, 123,
145-147, 152, 168-171, 177-178, 183-184, 186, 189-191, 193-194, 196-197
Switch Triggers ..............................................................................145-146, 171
System Design ..................................................................................................44
Margin Notes
Telephones ....................................................................156, 158, 191-192, 206
Test Equipment ........................................................................................97, 103
Test Lights ..............................................................................................109, 155
Time Alignment..............................................................................................137
Tools..............................................................85-86, 97, 109, 111-113, 115-119
Tracking System ............................................................................................153
Transceiver..............................................................................156-157, 179, 196
Transfer Function ..........................................................................................196
Transmission Line ..........................................................................................181
Transmitter ............................................151-152, 156, 176, 179, 190, 193, 196
Trigger................................................................64-65, 112, 146, 148-149, 176,
............................................................180-181, 186-187, 189, 193, 195-198
Troubleshooting ............................................................................26, 45-46, 52,
................................................................77, 96-97, 100, 103, 119, 146, 155
Trunk Release ................................................................................................197
Tweeter ................................................48-49, 51, 59-61, 78, 81, 141, 180, 197
Ultrasonic Sensor ..................................................................................149, 197
Universal Timers ............................................................................................153
VWXYZ
Vehicle ..........................................27-29, 36, 52, 55, 57, 65, 67, 69-70, 75-77,
............84-92, 94, 98-99, 101-102, 104, 106, 109, 115, 118-122, 125, 139,
............142, 144, 146-157, 161-164, 166-171, 173, 176-179, 181-198, 204
Voice Coil ..............38, 42, 58-59, 107, 176, 182, 186, 189, 191, 195, 197-198
Volt ..................................................................34-35, 37, 42, 55-56, 58-59, 65,
....................................................70, 73, 77, 80-81, 104, 107, 177, 184, 197
INDEX
THE BASIC INSTALLER STUDY GUIDE
219
Margin Notes
Voltage......................................27-34, 36, 38-40, 42-44, 46, 48, 50, 52, 54-59,
..........................63-65, 67-70, 72-78, 80-81, 89, 97-98, 100, 103, 105-109,
..........................114, 121, 123, 133, 153, 157, 159, 168-169, 173, 176-178,
............................................................181-182, 184-185, 187, 189-192, 197
Voltage Drop ................................32, 42-43, 52, 54, 56, 69-70, 74, 77, 89, 197
Volt-Ohm-Meter ....................................................................................189, 197
Volts ....................................................29, 32-35, 38, 50, 54, 57, 59, 68, 73-74,
................................................80-81, 102-106, 108, 161, 168-170, 179, 189
Watt ............................................................34-36, 80, 113, 157, 187, 194, 198
Wattage................................................................................32, 36, 44, 113, 198
Wavelength ......................................................................94, 131-132, 137, 198
Wire ..................................26, 29, 32, 34, 36-38, 43, 47, 51, 53, 56-57, 69-70,
....................76-77, 80, 85, 87-93, 95, 98-99, 101, 106, 110, 118, 120-125,
....137, 147, 155-157, 162, 168-169, 177-178, 180, 185-187, 190-191, 197
Wire Gauge ..................................................................26, 36-38, 43, 77, 91-92
Woofer..................................................................................60-61, 81, 137, 198
Xmax ..............................................................................................................198
ZONE ............................................................................................................198
220
THE BASIC INSTALLER STUDY GUIDE
INDEX