GB GMT-319 User Manual [en, es, fr]

• Read this owners manual
thoroughly before use and save.

• Lea completamente este manual
del propietario antes del uso y
consérvelo como referencia.

• Avant de se servir du multimetre,
lire attentivement le present
manuel d’utilisation, et le
conserver.

GMT-319

Analog Multimeter

Owners Manual

Multímetro análoga

Manual del propietario

Multimètre analogue

Manuel d’utilisation

GMT-319 manual 7.08.qxp 7/2/08 3:50 PM Page 1

2

1. Introduction

The GMT-319 is an Analog Multimeter
capable of measuring 7 functions on 19
ranges. A mirror scale is provided to
reduce the possibility of parallax errors.
Small lightweight and rugged construction.
This meter was designed for the
homeowner, hobbyist and professional
needing to make electrical and electronic
equipment measurements.

1.1 Meter Functions

Needle

Analog
Scale

Mechanical
Zero
Adjust
Screw

Zero
Ohms

Adjust
ment

Input Jacks

Function/
Range
Selector
Switch

Contents

1. Introduction

1.1 Meter Functions

2. Specifications

2.1 For Your Safety

3. Operating Suggestions

3.1 Preliminary Adjustments

3.2 Internal Battery Condition

4. DC Voltage Measurement

4.1 Household Batteries

5. DC Milliamp Measurement

6. AC Voltage Measurement

6.1 Wall Receptacles

7. Resistance/Continuity
Measurement

7.1 Extension Cords

7.2 Fuses

7.3 Switches

8. Decibel Measurement
(Transistor Gain)

9. Battery and Fuse Replacement

10. Warranty

11. Disposal

1

Figure 1

Battery/
Fuse
Cover

Mirror

GMT-319 manual 7.08.qxp 7/2/08 3:50 PM Page 2

Use extreme caution when
using this multimeter. Improper use of
this meter can result in severe damage to
property, severe personal injury or death.
Follow all instructions and suggestions in
this operators manual as well as normal
electrical safety precautions. Do not use
this multimeter if you are unfamiliar with
electrical circuits and proper test procedures.

2.1 For Your Safety

The marking “ ” on the multimeter represents
Caution, risk of electric shock.

The marking “ ” on the multimeter represents Caution,
risk of danger, important information, refer to the manual.
In order to find out the nature of the potential HAZARD
and any actions which have to be taken consult the
manual in all cases where “ ” is marked.

The marking “ ” on the multimeter represents
Functional earth terminal.

The marking “ ” on the multimeter represents
Equipment protected throughout by DOUBLE
INSULATION or REINFORCED INSULATION.

Measurement category II is for measurements
performed on circuits directly connected to the low
voltage installation. Examples are measurements
on household appliances, portable tools and
similar equipment.

1)Use extreme caution when checking

electrical circuits.

2)

Do not stand in wet or damp
work areas when working with electricity.
Wear rubber-soled boots or shoes.

3) Do not apply more voltage

4

2. Specifications

Ranges: 19 measuring ranges
DC Voltage: 2.5 -10-50-250-1000 Volts
AC Voltage: 10-50-250-1000 Volts
DC Current: 5-50-500 milliAmps (fused)

10 Amps on a separate jack (fused)

Resistance (Ohms): Rx1 (resistance indicated multiplied by 1)

Rx10 (resistance indicated multiplied by 10)
Rx1K (resistance indicated multiplied by 1000)
10 Megohm Max

Continuity Buzzer: For audible continuity checks. Buzzer sounds at

less than 100 ohms.
Decibels: -8db to +62db on AC voltage ranges
Accuracy: DC voltage, Amps = ±4% full scale of range

AC voltage =± 5% full scale of range

Resistance = ±4° arc of scale length
Battery Test: 1.5 volt and 9 volt batteries
Sensitivity: 20,000 ohms per volt DC and 8000 ohms per volt AC
Function/Range Switch: 7 Functions, 20 Positions, 19 Measuring Ranges
Zero Ohms Located on the front left side of the housing.
Adjustment dial: Adjustment Dial is used to zero the needle indicator

on the ohms scale while shorting the test leads together.
Mechanical Zero Located directly below the center of the scale.
Adjustment Screw: Used to align needle on the zero settings for

accurate readings.
Mirrored Scale Plate: The mirror on the scale plate is used to line up the

needle with its reflection to improve the reading

accuracy by preventing parallax error.
Recessed Input Jacks: Negative (-) input jack for black test lead, positive (+)

input jack for red test lead. Separate jack for 10

Amp range.
Fuse Type: F500mA H, 250V, GB GF-0306
Power Source: Two 1.5V AAA (non-rechargeable) batteries
Test Lead Type: ETL, cETL, CE, CAT II 1000V, 10A
Size (L x W x H): approx 149mm x 97mm x 43mm
Weight: approx 250g (including batteries)
Agency Approvals: ETL, cETL, CE, CAT II 1000V
Operating Temperature: 64°F - 77°F (18°C - 25°C)
Note: Accuracy is given for one year, at 23°C ±2° RH<60%
This multimeter was designed to be safe at least under the following conditions:
Indoor Use
Altitude: up to 2000m
Pollution Degree: 2
Ingress Protection Degree: IP20

Important:

Read this operators manual thoroughly before
using this multimeter.This manual is intended
to provide basic information regarding this
multimeter and to describe common test
procedures which can be made with this unit.

Many types of appliance, machinery and
other electrical circuit measurements are
not addressed in this manual and should
be handled by experienced service
technicians.

3

!

WARNING

!

!

!

WARNING

!

WARNING

GMT-319 manual 7.08.qxp 7/2/08 3:50 PM Page 4

or current than the set range of the
multimeter will allow.

4) Do not touch the metal

probes of the test leads when making a
measurement.

5) Replace worn test leads. Do not use test

leads with broken or tattered insulation. Only
test leads meeting ETL, cETL, CE CAT II
1000V I0A can be used in this multimeter.

6) Discharge a capacitor before measuring it.

7) Remove the test leads from the circuit being

measured as soon as the test is completed.

8) Do not measure voltage

when the function/range switch is set on the
resistance (ohms), continuity, or the current
(mA/A) settings. Never measure current
when the meter is set on the resistance
range. Never measure AC voltage when the
meter is set on DC voltage or DCmA/A.
Setting the meter on the incorrect function
may burn out some of the internal circuitry
and may pose a safety hazard.

3. Operating Suggestions

1) Set the function/range switch to the proper

position before making a measurement.
When the voltage or current is not known, it
MUST be determined that the capacity of
the selected range will handle the amount of
voltage or current in the circuit (see #3
under

For Your Safety

). Always start with the
highest range in the function. If the
reading falls within the range of a lower
setting, reset the function/range switch to

!

WARNING

!

WARNING

65

the appropriate setting for greater accuracy.

2) Avoid placing the meter in areas where
vibration, dust or dirt are present. Do not
store the meter in excessively hot, humid
or damp places. This meter is a sensitive
measuring device and should be treated
with the same regard as other electrical
and electronic devices.

3) Using the meter in areas with high magnetic
fields can result in inaccurate readings. For
greatest accuracy, lay the meter flat on a
non-metallic surface.

4) When the meter is not in use, keep the
function/range switch in the OFF position.
This keeps the needle indicator from
deflecting or ”bouncing” excessively.

5) When disconnecting the test leads from
the unit, always grasp the leads where the
input jacks meet the meter housing. Never
pull the leads out of the jacks by the
insulated wire or transport the meter using
the test leads as a carrying strap.

6) Never immerse the meter in water or
solvents. To clean the housing use a damp
cloth with a minimal amount of mild soap.

7) If the resistance (ohms) function of the
meter is not going to be used for a week or
more, remove the internal batteries to avoid
potential leaks that may damage the unit.

3.1 Preliminary Adjustments

Fully seat the test leads in the correct input
jacks. If necessary, using a small flat tip
screwdriver, slowly turn the mechanical zero

GMT-319 manual 7.08.qxp 7/2/08 3:50 PM Page 6

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adjustment screw clockwise or counterclock­wise until the needle indicator is directly over
the three black zeros at the left end of the scale.

Analog Meter:

Reading the Scale

General

The first step in reading the analog scale is to
align the needle with the scale. This is
achieved by locating the mirror on the scale.
Line the needle up with its reflection. When
the reflection is hidden by the needle, the
needle is properly aligned.

Resistance (Ohms - Ω)

Use the top scale for reading the resistance.
If the meter is set to X1k, multiply the
resistance value by 1000Ω.

DC Voltage (V DC)

Use the middle scale directly below the mirror.
Match the dial setting to the highest number on
the scale. If the setting does not match one of
the numbers, use a scale that can be easily
multiplied to give the setting (i.e.- for 1000V, use
the 10V scale and multiply the reading by 100).

AC Voltage (V AC)

Use the same numbers and procedures as
used for the DC voltage setting, but use the
scale directly below the numbers.

DC Milliamps

Use the same scale and procedure as used
for the DC voltage setting.

Decibel Gain (dB) - see pg. 15

Use the scale marked dB to read decibels for
transistor gain. Use the chart at the right of
the scale for proper conversion.

3.2 Internal Battery Condition

Before making resistance or continuity tests,
check the condition of the internal battery. First
turn the function/range switch to a resistance
position. Short the test leads together and the
needle indicator should deflect to the right side
of the scale. Keep the test leads shorted
together while simultaneously turning the zero
ohms adjustment dial until the needle indicator
reads zero at the right side of the ohms
(green) scale. If the needle will not zero,
replace the battery with two new 1.5 volt AAA
size non-rechargeable batteries (see

Battery

Replacement

).

4. DC Voltage Measurement

1) Fully seat the test leads in the correct input
jacks, (-) black lead, (+) red lead.

2) Set the function/range switch to the
appropriate DC voltage range. If the voltage
is unknown, use the highest range. If the

DC

10

20

50

100

200

500

2K

5K

0K

6

8

1K

Resistance
(Ohms)
Scale

DC Voltage
& Milliamps
Scale

Common Markings
for both the AC & DC
Voltage Scales

AC Voltage Scale

dB Scale for Transistor

Gain Measurement

}

GMT-319 manual 7.08.qxp 7/2/08 3:50 PM Page 8

109

voltage applied falls within the range of a
lower setting, reset the function/range switch
to the appropriate setting for greater accuracy.

3) If the polarity of the circuit to be tested is
known, touch the black test lead to the
neutral side. If the polarity is unknown, touch
the test leads to opposite sides of the circuit.
If the needle indicator deflects to the left of
the scale, reverse the test leads.

Use the chart below as a guide to reading DC
voltage measurements:

DC V Read and

range following multiply

setting scale reading by:

2.5 0-250 Divide reading by 100
10 0-10 1
50 0-50 1

250 0-250 1

1000 10 100

4.1 Household Batteries

Set the function/range switch to 10V DC to
test household 1.5 volt through 9 volt batteries.
Touch the red (+) test lead to the (+) terminal
and the black (-) test lead to the (-) terminal
of the battery. Read the 0-10 scale to
determine the condition of the battery.

5. DC Milliamp Measurement

1) Fully seat the test leads in the correct input
jacks, (-) black lead, (+) red lead.

2) Set the function/range switch to the
appropriate DCmA setting.

3) Touch the test leads to the circuit in series (in
line with the circuit) so that the circuit current
passes through the multimeter in order to

make the measurement. If the needle indicator
deflects to the left, reverse the test leads.

DC mA Read and
range following multiply

setting scale reading by:

5 0-50 0.1

50 0-50 1

500 0-50 10

DC 10Amp Measurement

A separate input jack is provided for measurement
of DC current up to 10 Amps. Additionally, this
function is designed for intermittent use only.
Maximum contact of the test leads with the
circuit is 15 seconds, with a minimum
intermission time of 30 seconds between tests.
Set the function/range switch to the 10A range.
Touch the test leads to the circuit in the same
manner as instructed in DC MILLIAMPERAGE
MEASUREMENT. Read the 0-10 scale.

Common DC Milliamperage
Measurements

It is important to point out that milliamps can also
be expressed as thousandths of an Ampere;
therefore 500 milliamps is 500 thousandths of
one Amp.The 500mA function of your
multimeter is commonly used by electronics
repair technicians and hobbyists to troubleshoot
various low voltage circuits.Although not normally

Figure 2

GMT-319 manual 7.08.qxp 7/2/08 3:50 PM Page 10

1211

used for electrical troubleshooting around the
home, this function can be used to measure the
milliamperage draw of household items such as
flashlights, and other battery operated devices
that do not draw more than 500 mA. In fig. 2
the red (+) test lead is hooked up to the (+) ter­minal of the lantern battery while the black (-)
test lead is hooked up to the bulb.The meter
will indicate the milliamperage draw when the
flashlight switch is thrown in the ON position.

Do not apply voltage to the
test leads while the meter is set in the
mA/A range. See #8

For Your Safety.

6. AC Voltage Measurement

1) Fully seat the test leads in the correct input

jacks (-) black lead, (+) red lead.

2) Set the function/range switch to the

appropriate AC voltage range. If the
voltage is unknown, use the highest range.
If the voltage applied falls within the range
of a lower setting, reset the function/range
switch to the appropriate setting for
greater accuracy.

3) Touch the test leads to the circuit under

test. With AC voltage, the polarity of the
test leads is not a factor.

Use the chart below as a guide to reading
AC voltage measurements:

AC V Read and
range following multiply
setting scale reading by:

10 0-10 1
50 0-50 1

250 0-250 1

1000 0-10 100

Common AC Voltage Measurements

6.1 Wall Receptacles

If the receptacle is controlled by a switch, make
sure the switch is ON. Set the function/range
switch to 250V AC. Touch the test leads to the
“hot” and “neutral” slots of the receptacle (see
fig. 3A).The needle indicator should read 120V
AC on the 0-250 scale.To test for proper
grounding of the receptacle, touch one test lead
to the “hot” (narrow) side of the receptacle, and
the other test lead to the ground slot. The meter
should read 120V AC as before.

7. Resistance/Continuity Measurement

For resistance and continuity testing POWER
MUST BE OFF:

1) Fully seat the test leads in the input jacks (-)
black lead, (+) red lead.

2) Set the function/range switch to the appropriate
resistance and short the test leads together.
Using the zero ohms adjustment dial, slowly
turn the dial until the needle indicator reads -0­ohms at the right end of the ohms scale. If the
needle will not zero, replace the internal batter­ies with two new 1.5 volt AAA size non­rechargeable batteries (see

Battery

Replacement

).

3) Touch the test leads to the resistance or non­energized circuit to be measured. Measure the

!

WARNING

Figure 3

3A

3B

GMT-319 manual 7.08.qxp 7/2/08 3:50 PM Page 12

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13

value of the reading on the green ohms scale
and multiply the reading by 1000 in the X1K/10
in X10/1 in X1 position. If you’re making basic
continuity tests, the needle indicator should
move all the way to the right side of the ohms
scale if continuity exists.

Note: When switching the unit back and forth
from ohms to other functions, always zero the
needle indicator before taking another reading.
Failure to zero the needle before taking
resistance/continuity measurements will result in
inaccurate readings.

Continuity tests are probably the most frequently
performed electrical troubleshooting procedures
around the home. ALWAYS REMEMBER THAT

CONTINUITY CHECKS ARE TO BE MADE
WITH THE POWER TO THE CIRCUIT
TURNED OFF. Polarity of the test leads is not a

factor in making continuity checks.

7.1 Extension Cords

Unplug the cord. Set the function/range switch to
the Rx1 position. Touch one of the test leads to
one of the metal prong ends of the cord, and
insert the other test lead in either one of the
receptacle slots on the other end of the cord,
making sure the test lead is making good contact
with the receptacle (see fig. 4). If the needle
indicator does not move to -0- ohms, insert the

test lead into the other receptacle slot, again
making sure of good contact. If the needle
indicator still does not move the cord has a break
and should be replaced.

7.2 Fuses

Note: With the power OFF, always remove a
fuse from its socket before testing it.With
cartridge fuses, touch the test leads to each
end of the fuse (see fig. 5). If the fuse is good,
the needle indicator will move to -0- ohms. If not,
replace the fuse. On plug-type fuses, touch the
the test leads on the bottom contact and the
other on the threaded metal contact (see fig. 6).

7.3 Switches

Cut off the power source to the switch. If
necessary, remove the switch.Turn the switch to
the ON position and touch the test leads to the
switch terminals (see fig. 7). If the switch is
good, the needle indicator will move to -0­ohms. If not, replace the switch. On other
switches such as three-way light switches or
double pole double throw (ON-OFF-ON)
switches, each ON position will need to be
tested. Alternate the test leads between the

Figure 4

Figure 6Figure 5

Figure 7

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