AUTO RANGING
CAT III 600V
DIGITAL MULTIMETER
USER’S MANUAL
DMM45
Please read this manual carefully and thoroughly before using this product.
TABLE OF CONTENTS
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Key Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
What's in the Blister Pack . . . . . . . . . . . . . . . . . . . . . . . . . 4
Product Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 – 5
Safety Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 – 8
Setup Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Install Batteries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Operating Instructions . . . . . . . . . . . . . . . . . . . . . . . . 9 – 13
General Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Using Auto Ranging . . . . . . . . . . . . . . . . . . . . . . . 9
Turning On the Backlight . . . . . . . . . . . . . . . . . . . 9
Auto Power Off . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Measuring AC or DC Voltage . . . . . . . . . . . . . . . . . . . . . 10
Measuring AC or DC Current . . . . . . . . . . . . . . . . . 10 – 11
Measuring Resistance. . . . . . . . . . . . . . . . . . . . . . . . . . 11
Measuring Temperature . . . . . . . . . . . . . . . . . . . . . . . . 12
Checking for Continuity. . . . . . . . . . . . . . . . . . . . . . . . . 12
Checking the Integrity of a Diode . . . . . . . . . . . . . . . . . 13
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 – 15
Operating & Maintenance Tips. . . . . . . . . . . . . . . . . 15 – 16
Replacing the Fuse. . . . . . . . . . . . . . . . . . . 15 – 16
Warranty Information . . . . . . . . . . . . . . . . . . . . . . . . 17 – 18
Return for Repair Policy . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2
INTRODUCTION
Thank you for purchasing General Tools & Instruments’
(General’s) DMM45 Auto Ranging CAT III 600V Digital
Multimeter. Please read this user’s manual carefully and
thoroughly before using the instrument.
The DMM45 is designed for use in an industrial setting by
HVAC/R contractors, building maintenance technicians, MRO
(maintenance, repair and operations) personnel at process
and power plants, electricians, and electrical/electronic
technicians.
The meter is affordable, reliable, easy to use, ruggedly built
and designed to meet the CAT III 600V safety standard.
KEY FEATURES
• 8 functions, 25 ranges
• Measures 1) AC voltage over five ranges, 2) DC voltage
over five ranges, 3) DC current over four ranges, 4) AC
current over four ranges, 5) resistance over six ranges,
and 6) temperature over one range using included “K”
type stem thermocouple probe
• Uses beeper to 7) verify integrity of diodes and 8) check
circuits for continuity
• Large backlit 3-1/2 digit (2,000 count) LCD
• LIGHT (backlight) button
• 15 minute Auto Power Off (APO)
• Designed to meet CAT III 600V safety standard
• 1 year limited warranty
3
WHAT’S IN THE BLISTER PACK
The meter is supplied in a blister pack with a cavity in the
rear. Inside the cavity are a pair of double-insulated 20AWG
test leads, a “K” type stem thermocouple probe, and two
“AAA” batteries. This user’s manual is supplied inside the
fold-over blister card.
PRODUCT OVERVIEW
Fig. 1 shows the labels and positions of the controls,
indicators and physical structures of the DMM45. Fig. 2
shows all possible indications on the meter’s LCD. Familiarize
yourself with the functions and meanings of these controls,
indicators and connectors before moving on to the Setup
Instructions and Operating
Instructions.
1
Fig. 1. The controls, indicators
and physical structures
3
2
of the DMM45.
1. LCD
4
2. LIGHT button. Pressed and
held for >3 seconds, turns
on display backlight for 15
seconds. Pressed and held
5
with backlight on, turns
backlight off.
3. SHIFT button. Used to toggle between 1) AC and DC current
measurement modes, 2) continuity and diode integrity
check modes, and 3) °F or °C display of temperature
4. Rotary function switch
5. Jacks for test leads
}
4
Fig. 2. All possible display indications
SAFETY INSTRUCTIONS
•WARNING
To avoid possible electric shock or personal injury, and to
avoid damaging the meter or the equipment under test:
• Do not use the meter in any way not detailed in this manual
or the meter's safety features may be compromised.
• Before using the meter, inspect the case.
Do not use the meter if it is damaged. Look for cracks or
missing plastic. Pay particular attention to the area near the
test lead jacks.
• •WARNING Inspect the test leads for damaged insulation
or exposed metal. Check the test leads for continuity.
Replace damaged leads before using the meter.
• Verify the meter’s operation by measuring a known voltage.
Do not use the meter if it operates abnormally. Protection
may be impaired. When in doubt, have the meter checked
and serviced by a qualified technician.
• •WARNING Do not apply more than the rated voltage, as
marked on the front of the meter, between the terminals or
between either terminal and ground.
5
• •WARNING Do not measure current above 600V in
Category III installations.
• •WARNING Do not measure voltage with the rotary
function switch in any resistance (ohms) or current position.
Doo not measure current with the rotary function switch in
any resistance position.
• Use caution when working with voltages above 42VACRMS,
or 60VDC. These voltages pose a shock hazard.
• Use the proper terminals, function, and range for all
measurements.
• •WARNING Do not operate the meter around explosive
gas, vapor, or dust.
• •WARNING When using the test leads, keep your fingers
behind the finger guards. Do not touch the metal probes of
the test leads when making a measurement.
• When making connections, connect the black (–) test lead
before connecting the red (+) test lead; when
disconnecting, disconnect the red (+) test lead before
disconnecting the black (–) test lead.
• Disconnect circuit power and discharge all high-voltage
capacitors before measuring/testing for resistance,
continuity or diodes.
• Before making DC voltage measurements, verify that AC
voltages are not present by making measurements in AC
voltage mode. Then select a DC voltage range equal to or
greater than the AC range.
• Before measuring current, turn off power to the circuit
before connecting the meter.
• Do not operate the meter with the case (or part of the case)
removed.
6
• Use only two “AAA” batteries, properly installed in the
battery compartment, to power the meter. Do not use
rechargeable batteries.
• Replace the batteries as soon as the low battery indicator
“
” appears on the LCD. Operated with weak batteries,
the meter might produce false readings that could lead to
electric shock and personal injury.
• Remove the test leads from the meter before opening the
meter meter’s or battery compartment.
Electrical Symbols Used On the Meter
and In This Manual
Symbol
Description
Symbol
Description
AC (Alternating
Current)
Fuse
DC
(Direct Current)
Double
Insulated
Caution, risk of
electric shock.
Hazardous
voltage.
Risk of danger.
Important
information.
Refer to the
manual.
Battery
(Low battery)
when shown
on display
Earth ground
Diode
Continuity Beeper
AC or DC
Complies with EU directives
7
Symbol Description
Application and
removal from
hazardous live
conductors
permitted
Symbol
Description
For measurements
made on building
equipment such
as distribution
panels, feeders
and short branch
circuits, and on
lighting systems in
large buildings.
SETUP INSTRUCTIONS
INSTALL BATTERIES
The DMM45’s battery compartment is located at the bottom
rear of the meter.
To open the compartment, use a small Phillips-head
screwdriver to remove the three silver screws securing the
battery compartment cover. Put the screws and the cover to
the side and take care not to lose the small screws.
Remove the two “AAA” batteries from the rear cavity of the
blister pack. Install them in the battery compartment, taking
care to observe the polarity markings inside the
compartment.
Replace the battery compartment cover and secure it with the
three Phillips-head screws.
8
OPERATING INSTRUCTIONS
GENERAL INSTRUCTIONS
Using Auto Ranging. The DMM45 is an auto ranging
multimeter that cannot be operated in manual ranging mode.
The meter automatically chooses the full-scale measurement
range that maximizes measurement resolution for all
measured parameters (except temperature, for which there
is only one full-scale range). The Specifications section on
pages 14 & 15 lists the full-scale ranges (and their
resolutions) available for measuring DC volts, AC volts,
AC amps, DC amps and resistance (in ohms).
Turning On the Backlight
Pressing and holding the LIGHT button (Fig. 1, Callout 2) for
at least 3 seconds turns on the LCD’s bright white backlight,
making measurements much easier to read in dark spaces.
To extend battery life, the backlight is automatically turned
off after 15 seconds.
Auto Power Off
The DMM45 is equipped with an Auto Power Off (APO) circuit
that automatically powers off the meter if no front-panel
button is pressed within any span of 15 minutes. The purpose
of the APO feature is to extend battery life.
The meter announces that APO shutdown is imminent by
producing five short beeps after 14 minutes of inactivity.
To keep the meter from shutting down, immediately press the
LIGHT button or change the position of the rotary function
switch. After 15 minutes of inactivity, the APO function will
shut down the meter and announce the action with a long
beep.
9
MEASURING AC OR DC VOLTAGE
WARNING Do not measure any voltage higher than 500V. Doing so may
blow the meter’s internal fuse and/or damage the meter’s
internal circuitry.
(1) Set the rotary function switch to the (DC voltage) or
(AC voltage) position. If you choose the position, DC
will appear on the left side of the LCD (see Fig. 2). If you
choose the
position, AC will appear on the left side of
the LCD.
(2) Plug the red test lead into the V/Ω/mA jack on the front of
the meter and the black test lead into the COM jack.
(3) Touch the black test lead to the lower-potential point of
the circuit under test, and the red test lead to the higherpotential point.
(4) Read the measured voltage amplitude on the LCD. If the
test leads are reversed, a minus sign will appear at the left
of the displayed value.
MEASURING AC OR DC CURRENT
WARNING Before inserting test leads into a circuit, remove power from
the circuit.
(1) Set the rotary function switch to the
position.
(2) Using the SHIFT button, select DC or AC current
measurement mode (indicated by the presence of DC or
AC on the left side of the LCD).
(3) Plug the red test lead into the V/Ω/mA jack on the front of
the meter and the black test lead into the COM jack.
10
(4) Connect the test leads in series with the device whose
current flow you wish to measure.
(5) Read the measured current amplitude on the LCD. If the
test leads are reversed, a minus sign will appear at the left
of the displayed value. If the amplitude of the current you
are measuring is greater than 200mA, OL (for overload)
will appear on the LCD. If your readings are consistently
less than 0.2mA, turn the rotary function switch to the
position to improve your measurement resolution.
MEASURING RESISTANCE
WARNING To avoid electrical shock or damage to the meter when
measuring resistance or continuity in a circuit, make sure the
power to the circuit is turned off and all capacitors are
discharged.
(1) Turn the rotary function switch to the Ω position.
(2) Plug the red test lead into the V/Ω/mA jack on the front of
the meter and the black test lead into the COM jack.
(3) Measure the resistance by touching the tips of the leads
across the resistor or between the desired test points of
the circuit, as shown below.
RED TEST LEAD
BLACK TEST LEAD
(4) Read the measured resistance on the LCD. If the
measured resistance is greater than 20MΩ, O.L will
appear on the LCD to indicate an overload.
11
MEASURING TEMPERATURE
(1) Turn the rotary function switch to the °F or °C position.
(2) Plug the two-prong connector of the supplied “K” type
thermocouple probe into the jacks on the front of the
+ into the
meter. Make sure to plug the prong labeled 쎻
V/Ω/mA jack and the prong labeled 쎻
- into the COM jack.
(3) Read the temperature on the LCD. To quickly switch from
°F to °C or vice-versa, press the SHIFT button.
CHECKING FOR CONTINUITY
(1) Turn the rotary function switch to the
position. An
icon of a diode will appear at the lower left of the LCD.
(2) Press the SHIFT button. The icon of a diode will change to
the continuity icon (
). Until the test leads are plugged
into the meter’s front-panel jacks, OL. will appear on the
LCD to indicate an open circuit.
(3) Plug the red test lead into the V/Ω/mA jack on the front of
the meter and the black test lead into the COM jack.
(4) Touch the test leads to any two points of a circuit. If the
resistance between those points is <30Ω, the beeper will
sound continuously. If there is no continuity (an open
circuit or a resistance greater than 30Ω between the two
points), OL. will appear on the LCD.
12
CHECKING THE INTEGRITY OF A DIODE
(1) Turn the function switch to the
position. An icon of
a diode will appear at the lower left of the LCD. Until the
test leads are plugged into the meter’s front-panel jacks,
.OL will appear on the LCD to indicate an open circuit.
(2) Plug the red test lead into the V/Ω/mA jack on the front of
the meter and the black test lead into the COM jack.
(3) Connect the red test lead to the anode (positive terminal)
of the diode to be tested, and the black test lead to its
cathode (negative terminal).
RED TEST LEAD
BLACK TEST LEAD
(4) Read the forward bias voltage value on the LCD. A silicon
diode typically has a forward bias voltage of 0.7V. A
germanium diode typically has a forward bias voltage of
0.3V. A 0V reading in both directions indicates a shorted
diode. A reading of 1 indicates an open diode. In either
case, the diode is defective and should be replaced.
13
SPECIFICATIONS
Parameter or
Feature/Function
AC voltage
DC voltage
AC current
DC current
Resistance
14
Specification
Measurement
ranges
Measurement
resolutions
Measurement
accuracy
Measurement
ranges
Measurement
resolutions
Measurement
accuracy
Measurement
ranges
Measurement
resolutions
Measurement
accuracy
Measurement
ranges
Measurement
resolutions
Measurement
accuracy
Measurement
ranges
Measurement
resolutions
Measurement
accuracy
Value
0 to 200mV/2V/20V/200V/500V
0.1mV/1mV/10mV/100mV/1V
±(0.8% of reading + 5 digits)
0 to 200mV/2V/20V/200V/500V
0.1mV/1mV/10mV/100mV/1V
±(0.5% of reading + 5 digits)
0 to 200μA/2mA/20mA/200mA
0.1μA/1μA/10μA/100μA
±(1.8% of reading + 3 digits)
0 to 200μA/2mA/20mA/200mA
0.1μA/1μA/10μA/100μA
±(1.8% of reading + 2 digits)
0 to 200Ω/2kΩ/20kΩ/200kΩ/2MΩ/20MΩ
0.1Ω/1Ω/10Ω/100Ω/1kΩ/10kΩ
±(1.5% of reading + 2 digits)
Parameter or
Feature/Function
Temperature
Specification
Measurement
range
Measurement
resolution
Measurement
accuracy
Value
-40° to 752°F (-40° to 400°C)
1° (F or C)
±(8% of reading + 8 digits) below
32°F (0°C); ±(1.2% of reading +
7 digits) from 32° to 212°F (0° to
100°C); ±(3% of reading + 3 digits)
from 212° to 752°F (100° to 400°C)
Continuity threshold
<30Ω
Overload protection level
600VAC/DC
Input impedance
10MΩ
Frequency response
50/60Hz
Ingress protection (IP) rating
IP20
Safety rating
CAT III 600V
Test leads
Double-insulated, 20 AWG,
1A max rating
Display
No. of digits
3-1/2
Maximum count
2000
Size
2.4 x 1 in. (62 x 26mm)
Digit height
0.63 in. (16mm)
Auto Power Off trigger
15 minutes of front-panel inactivity
Backlight duration
15 seconds
Operating temperature
32° to 122°F (0° to 50°C)@<75%RH
Operating altitude (max)
6562 ft. (2000m)
Dimensions
8.86 x 3.31 x 1.30 in.
(225 x 84 x 33mm)
Weight (including batteries)
6.3 oz. (179g)
Power source
(2) “AAA” batteries (IEC LR03)
Battery life
200 hours (typical)
Note: Accuracy values stated for operation at 23° ±3°C @<70%RH
15
OPERATING & MAINTENANCE TIPS
When the
icon appears at the upper right of the LCD
(see Fig. 2), it’s time to replace the two “AAA” batteries that
power the meter (although measurements will remain valid
for several hours after the icon first appears). To replace the
batteries, follow the instructions on p. 8.
Do not operate the DMM45 in the presence of a flammable or
explosive gas or near an arc welder or induction heater.
After subjecting the meter to a large change in ambient
temperature, wait at least 30 minutes before making
measurements to guarantee the accuracy of readings.
Remove the batteries when storing the meter or when you do
not expect to use it for an extended period of time (months
rather than weeks).
Do not disassemble the DMM45 or immerse it in water.
REPLACING THE FUSE
The DMM45 is equipped with a 200mA/250V cylindrical fuse
in series with the V/Ω/mA jack.
The fuse is located in the battery compartment, above the
two “AAA” batteries (see photo below).
16
To replace the fuse, open the battery compartment by
removing the three screws securing its cover. Be careful not
to shatter the glass of the blown fuse when removing it, and
take care not to lose the small screws after opening the
compartment.
WARRANTY INFORMATION
General Tools & Instruments’ (General’s) DMM45 Auto
Ranging CAT III 600V Digital Multimeter is warranted to the
original purchaser to be free from defects in material and
workmanship for a period of one year. Subject to certain
restrictions, General will repair or replace this instrument if,
after examination, the company determines it to be defective
in material or workmanship. The warranty period begins on
the date of purchase. You are encouraged to register your
product online. General will extend your warranty an
additional 60 days if you register at
www.generaltools.com/ProductRegistry.
This warranty does not apply to damages that General
determines to be from an attempted repair by non-authorized
personnel or misuse, alterations, normal wear and tear, or
accidental damage. The defective unit must be returned to
General Tools & Instruments or to a General-authorized
service center, freight prepaid and insured.
Acceptance of the exclusive repair and replacement remedies
described herein is a condition of the contract for purchase of
this product. In no event shall General be liable for any
incidental, special, consequential or punitive damages, or for
any cost, attorneys’ fees, expenses, or losses alleged to be a
consequence of damage due to failure of, or defect in any
product including, but not limited to, any claims for loss of
profits.
17
Register now at www.generaltools.com/ProductRegistry to
receive a 60-day extension to your warranty.
RETURN FOR REPAIR POLICY
Every effort has been made to provide you with a reliable
product of superior quality. However, in the event your
instrument requires repair, please contact our Customer
Service to obtain an RGA (Return Goods Authorization)
number before forwarding the unit via prepaid freight to the
attention of our Service Center at this address:
General Tools & Instruments
80 White Street
New York, NY 10013
212-431-6100
Remember to include a copy of your proof of purchase, your
return address, and your phone number and/or e-mail
address.
18
NOTES
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GENERAL TOOLS & INSTRUMENTS
80 White Street
New York, NY 10013-3567
PHONE (212) 431-6100 FAX (212) 431-6499
TOLL FREE (800) 697-8665
e-mail: sales@generaltools.com
www.generaltools.com
DMM45 User’s Manual
Specifications subject to change without notice
©2013 GENERAL TOOLS & INSTRUMENTS
NOTICE - WE ARE NOT RESPONSIBLE FOR TYPOGRAPHICAL ERRORS.
MAN# DMM45
10/03/13