RADIO & TELEVISION
THEORY - I
INTRODUCTION TO ELECTRICITY:
What is Electricity.
DIRECT AND ALTERNATING VOLTAGE:
Current, DC Voltage, Closed circuit, AC Voltage, Open circuit, Frequency,
Short circuit, Time period.
Ohm’s law: Ohm’s law Definition, Formula, Power.
RESISTORS:
Colour code Identification, Fixed Resistors Symbols, Variable Resistors,
special type -symbols, LDR, VDR, PTC, NTC, Symbols, Unit, Effect of
Resistor on DC & AC applications, Series and Parallel Circuits, Wattage and
Size, Defects and checking method.
CAPACITORS:
Types of Insulators, Types of Capacitor, Symbos & Units, Fixed: Polarity
Capacitors, Electolytic, Tantalum, Non-Polarity Capacitor, Paper, Polyster,
Polypropelene ceramic- Disc- Tubular-Pin-Up, Mica, Styroflux, Variable: Air
Gang, PVC Gang, Gang with Trimmer, Semi Variable: Trimmer Capacitor,
Padder Capacitor.
Capacitor Colour code Chart: Methods to find our values from different
capacitors, tolerances, Working Voltage, Temperature Co-efficient.
Behaviour of a capacitor on DC and AC, Frequency Effect, Applicationhfunctions, Series and Parallel Circuits, General Defects in a Capacitors,
Checking Methods.
COILS & TRANSFORMERS:
Conductor, Turns/Winding,Types of Cores: Air Core, Laminated Iron Core,
Brass Core, Ferrite Core, Type of formers: E-Type, I-Type, Types of
Transformer: Step up, Step down.
High Frequency Transformers: Intermediate Frequency Transformer (IFT):
Antenna Coils, Oscillator Coils. Behaviour of a Coil on DC and AC, General
Defects in a coil and Transformer, Checking Methods.
SEMI CONDUCTORS:
Difference between Conductor and Semiconductor, Examples of
Semiconductors, P-Type Semiconductor, N-Type Semiconductor, Types of
Diodes: Power Diodes, Frequency Diode, Varactor Diode, Light Emitting
Diode, Zener Diode, Detector Diode, Photo Diode, Application & Functions
of Diode, Voltage regulation with Zener Diode, Types of Defects, Checking
methods, Transistors: NPN Transistors, PNP Transistors, Current path in
NPN & PNP Transistor. Working of a Transistor as an Amplifier, Amplifier
Principles(NO NEED TO USE CALCULATIONS AND FORMULAE)
Types of coupling in Amplifiers: R-C Coupling, Transformer Coupling, Direct
Coupling, Merits and Demerits of The Three couplings. Push-Pull Output
Amplifier, Complimentary Symmetry Output Amplifier, Fault Finding in a
Single Stage Amplifier using NPN Transistor, Defects in a Transistor,
Checking method to test a transistor.
THYRISTORS: SCR, DIAC, TRIAC, Symbols and their Application.
OPTO ELECTRONIC DEVICES ONLY SYMBOLS & APPLICATION:
Light Emitting Diode, Photo Diode, Photo Transistor, Optocoupler/Photo
coupler.
AN INTRODUCTION TO INTEGRATED CIRCUITS: Single in line package
IC, Dual in Line Package IC, Quad in line package IC.
POWER SUPPLY- RECTIFIER CIRCUITS:
Half Wave Rectifier, Full Wave Rectifier, Bridge Rectifier, Filterr circuit,
Comparison of Rectifier circuits, 1.5V & 12V Battery, Eliminator using Bridge
Rectifier, Simple IC regulated Power Supply, Fault Finding Methods.
OSCILLATORS:
Electrical oscillator- How it works, Crystal Oscillator.
SOLID STATE RADIO RECEIVER
INTRODUCTION:
Audible Frequencies, Modulation: Amplitude Modulation, Frequency
Modulation, Propagation of Radio waves: Ground waves, Sky Wave, Line of
Sight Waves, Radio Transmission: Simple block diagram, Superhetrodyne
Principle, Complete Super-hetrodyne Radio receiver Block diagram, RF &
Frequency Convertor Section, IF Amplifier & Detector Section, AGC, Audio
Driver and Output Section, Single Band & Multi Band Circuit Diagrams:
Discrete Circuit, IC type circuit, FM Radio Receivers, Modern Radio
Receivers: Auto Search Tuning, Station Memory, Preset, Timer,
Mono/Stereo FM Trouble Shooting Techniques, Alignments Test
Equipments & Checking methods: IF Alignment Procedure, RF Alignment
Procedures, Signal Generator, Oscilloscope, Multimeter Analogue and DMM.
TAPERECORDER & CD MUSIC SYSTEMS TAPE RECORDER
INTRODUCTION:
Types of Tape Recorder: Spool Tape Recorders, Cartridge Tape Recorders,
Compact Cassette Micro Cassette, Dictaphone, Walkman, Various controls,
Selector Switches & their functions, Magnetic Principles: Temporary
Magnets, Permanent Magnets; Principles of RECORDING-PLAYBACKERASING, Recording: R/P Head, How signal is Recorded on a Tape, Types
of Biasing: Playback, Erasing: Types of Erasing ; The Complete Block
Diagram of a Mono Tape Recorder, Types of Audio Heads: Mono-stereo R/P
Heads and Erase Heads, Head Azimuth Alignment, Double Tape Deck with
Radio, High Speed Dubbing, Graphic Equalizer, Auto Reverse, Dobly NRnoise reduction; Car Stereo Cassette Player: Remote, Woofer, Tweeter
Speakers; Walkmans: with AM/FM Radio; Tape Transport Mechanism,
Motors, Servicing of Tape Drive Mechanism: Dirty Heads, Worn out heads,
No movement of Tape: Tape spills, Wobbling, Wow and Flutter, Worn out or
Loose belt, Defective motor, Motor Rotates at high Speed, Whistling noise
on playback, No FF, No Rew, No Auto Stop.
CD PLAYERS
An Introduction to CD Systems, Principles of CD Playback, Block diagram of
a CD Player, Special Features and their controls: Top loading, Play/Next,
Repeat, Pause Error, AMS Auto Music Search: Go to previous track, go to
Next Track: Select, Program, Store, Cancel, Reset, Anti-shock Switch.
SERVICING A CD PLAYER:
Safety handling, Checking & Adjusting Lazer diodes, Cleaning the CD, Pick
up lens cleaning, Alignment & Mechanical adjustment, Tray does not open or
close, Tray opens but not fully, Tray opens fully but the loading motor does
not stop. The CD goes in and ejects automatically, No disc display, Display
normal, CD loads but does not Play, Skip problem, Display shows “error”
after a disc is placed player also does not work, CD player appears to
operate but there is no sound output, Disc Rotates at high speed.
Test Equipments for servicing tape recorders and CD Music System: Analog
Multimeter, Digital Multimeter, Oscillator, Logic proble, Frequency Counter.
RADIO & TELEVISION
THEORY - II
SOLID STATE TELEVISION RECEIVERS- MONOCHROME & COLOUR
TELEVISION FUNDAMENTALS:
The scanning Process, Horizontal and Vertical scanning, Flickering,
Interlaced Scanning & their Frequencies, H & V Blanking, H & V
Synchronisation, Aspect Ratio, Picture Quality, The complete composite
video signal.
ESSENTIAL OF MONOCHROME TRANSMISSION:
Standards: Picture-AM, Sound-FM, Intercarrier Sound System, TV broadcast
Band and its channels.
FREQUENCIES: VIF Frequency, SIF Frequency, SHF Frequency
Monochrome Television Receiver, Complete Block Diagram of a Solid State
TV Receiver Set: VHF/UHF Tuners- RF Amplifier, Mixer & Local Oscillator:
Manual Type Tuner, Electronic Tuners, S-Band Tuners, Hyper Band Tuners
VIF Amplifier, Picture AM Detector, AGC, Video Amplifier & CRT, SHF
Amplifier, FM Detector, Audio amplifier, Sync Separator, AFC, Horizontal
Sweep Section, EHT Generation, Vertical Sweep Section, Deflection Yoke.
PRINCIPLES OF COLOUR:
Primary Colors, Secondary Colors, Luminance, Hue, Saturation, Colour
mixing, Basic Elements of Colour Transmission: Simple Block diagram of a
Colour TV Transmitter: The different Systems and standards in Color
Television: Overview of the Three systems- NTSC, PAL, SECAM, Merits and
Demerits of PAL System, CCIR Standards and Specifications; block diagram
of PAL Colour TV Receiver: RF Tuner, Vision IF, Complete, Sound Section,
Chroma Section, RGB Video Amplifiers, Color picture tube, Line section &
EHT Generation, Frame Section, Power supply.
DIFFERENT TYPES OF COLOUR CRTs: PIL Precision In Line Picture
Tube, Trinitron colour Picture Tube; Power Supplies: Series Regulated
Power Supply, SCR Power supply, Switched Mode Power Supply, STR
Power Supply, Television Receiving Antennas: Folded Dipole Antenna;
Remote Controls: Operating Controls in Remote Handset Unit, Block
diagram of Remote Transmitter Unit, Working principles of Remote
controlled Handset and its receiving Unit, On Screen Display, Auto Search
tuning, TV Lock, Child Lock, Tuning Lock, SWAP functions, SKIP Functions,
Sleep Timer.
Trouble Shooting - Fault Finding analysis: Different Procedures, Methods of
Approach: Observation, Smelling, Voltage measurements, Current &
Resistance measurements, Safety Precautions; Updating CTV’s with latest
Remote Control, Test instruments Equipments used for color television
servicing: Analog Multimeter, Digital Multimeter, Color Pattern Generator,
Cathode Ray Oscilloscope, Market Generator, Signal Injector Frequency
Counter.
V- VIDEO CASSETTE RECORDER
INTRODUCTION TO A VCR:
What is a VCR? Frequency & Bandwidth of the signals used in VCR,
Various types of Heads & motors used in a VHS-VCR.
BASIC PRINCIPLES OF A VCR:
Magnetic Principles, Recording, Playback & Erasing, Signals & Pulses
recorded on a VHS format Tape. Simple Block Diagram of a VHS format
VCR, Tape Transport Mechanism, Mechanical Alignments and Adjustments,
Electrical Alignments and Adjustments, Salient Features Present in modern
Video Cassette Recorders, Test Equipments & Trouble shooting.
VCD & LD PLAYERS
(Video Compact Disc Player and Laser Disc Player)
INTRODUCTION:
What is VCD Player and What is LD Player?
Principles of operation of Laser Unit device, Working Principles, Different
types of Motors for Loading, Stepper/Selector, Spindle, Transport
Mechanism-Gears, Belts, Motors, alignment Techniques.
SALIENT OPERATION FEATURES:
Open, Close, Play, Pause, All Repeat, Repeat, Time, Shuffle, Random, Edit,
LD Disc Slide A/B, Direct CD, Scan Rev, Scan FWD
GENERAL SYMPTOMS OF FAULTS:
No Disc Display, Loading problems, Selector problems, Skipping problems,
Dead-power supply, No Disc appears after playing few tracks, While playing
Disc ejects automatically, Alignment problems.
TEST INSTRUMENTS- EQUIPMENTS USED:
Analog Multimeter, Digital Multimeter, Cathode Ray Oscilloscope, Logic
Probe.
REFERENCE:
Author’s Name: Mr. N. C. Goyal, Mr. S.K.Mukherjee Sharma & Mr. G.K.
Mithal