Tenma 72-7930 Operating Manual

Table of Contents

Title Page

Overview
Inspection
Safety Information
Safe Operation
International Electrical Symbols
The Meter Structure
Rotary Switch Positions
Functional Button Operation
Display Symbols
Measurement Operation
A. DC and AC Voltage Measurement
B. DC and AC Current Measurement
C. Measuring Resistance
D. Measuring Diodes
E. Testing for continuity
F. Capacitance measurement
G. Temperature Measurement
H. Measuring Transistors
I. Frequency Measurement
Sleep Mode
Operation of Hold Mode
General Specifications
Accuracy Specifications
A. DC Voltage
B. AC Voltage
C. DC Current
D. AC Current
E. Resistance Test
F. Diodes Test
G. Continuity Test
H. Capacitance
I. Temperature
J. Transistor Test

3

10

4

11

12
14

14
15

17
18

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21

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23

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26

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29

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5
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Title Page

K. Frequency
Maintenance
A. General Services
B. Replacing the Fuses
C. Replacing the Battery

31
32
32

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Overview

Warning
To avoid risk of injury from electric shock, read the
“Safety Information” and “Rules For Safe Operation”
carefully before using the meter.

The Digital Multimeter Model 72-7930 (hereafter referred
to as The Meter) is a highly reliable handheld measuring
instrument featuring an extra large LCD 3-1/2 digit display
and full range overload protection. It is capable of
measuring AC/DC voltage, AC/DC current, resistance,
capacitance, temperature, frequency, Transistor HFE,
diode and continuity check. It also features a full icon
display with proper test lead indication.

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Inspection

In the event items are missing or damaged, please
contact your dealer immediately.

1 Operating Manual
2 Test Leads
3 Multi-Purpose Socket
4 Point Contact Temperature Probe
5 9V Battery (NEDA 1604, 6F22 or 009P)

This meter includes the following items:

1 piece
1 pair
1 piece
1 piece
1 piece

Item

Description

Qty

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Safety Information

This Meter complies with the standards IEC61010: in
pollution degree 2, overvoltage category (CAT. II 1000V,
CAT. III 600V) and double insulation.

CA T. II: Local level, appliance, PORTABLE EQUIPMENT
etc., with smaller transient voltage overvoltages than
CAT. III
CAT. III: Distribution level, fixed installation, with smaller
transient overvoltages than CAT. IV

Use the Meter only as specified in this operating manual,
otherwise the protection provided by the Meter may be
impaired.

In this manual, a Warning identifies conditions and
actions that pose hazards to the user, or may damage
the Meter or the equipment under test.

A Note identifies the information that user should pay
attention to.

International electrical symbols used on the Meter and
in this Operating Manual are explained on page 8.

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Warning
To avoid possible electric shock or personal injury,
and to avoid possible damage to the Meter or to the
equipment under test, adhere to the following rules:

l Before using the Meter inspect the case. Do not
use the Meter if it is damaged or the case (or part
of the case) is removed. Look for cracks or missing
plastic. Pay attention to the insulation around the
connectors.
l Inspect the test leads for damaged insulation or
exposed metal. Check the test leads for continuity .
Replace damaged test leads with identical model
number or electrical specifications before using
the Meter.
l Do not apply more than the rated voltage, as
marked on the Meter, between the terminals or
between any terminal and ground.
l The rotary switch should be placed in desired
position prior to connecting leads. This position
should not be changed while leads are connected.
l When using the Meter at an effective voltage
over 60V DC or 30V rms AC, special care
should be taken for there is danger of electric
shock.
l Use the proper terminals, function, and range
for your measurements.
l If the value to be measured is unknown, use the
maximum measurement position and reduce the
range step by step until a satisfactory reading is
obtained.
l Do not use or store the Meter in an environment
of high temperature, humidity , explosive, inflammable
and strong magnetic field. The performance of
the Meter may deteriorate after dampened.

Safe Operation (1)

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Safe Operation (2)

l When using the test leads, keep your fingers
behind the finger guards.
l Disconnect circuit power and discharge all high

-voltage capacitors before testing resistance,
continuity, diodes, capacitance or current.
l Before measuring current, check the Meter’s
fuses and turn off power to the circuit before
connecting the Meter to the circuit.
l Replace the battery as soon as the battery indicator
appears. With a low battery, the Meter might
produce false readings that can lead to electric
shock and personal injury.
l Remove test leads, test clips and temperature
probe from the Meter and turn the Meter power
off before opening the Meter case.
l When servicing the Meter, use only the same
model number or identical electrical specifications
replacement parts.
l The internal circuit of the Meter shall not be altered
at will to avoid damage of the Meter and any
accident.
l Soft cloth and mild detergent should be used to
clean the surface of the Meter when servicing.
No abrasive and solvent should be used to prevent
the surface of the Meter from corrosion, damage
and accident.

l The Meter is suitable for indoor use.
l Turn the Meter power off when it is not in use

and take out the battery when not using for a long
time.
l Constantly check the battery for leaks, replace
the battery if leaks appear. A leaking battery will
damage the meter.

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International Electrical Symbols

AC (Alternating Current).
DC (Direct Current).
Ground.
Double Insulated.
Low Battery.
Warning. Refer to the Operating Manual.
Conforms to Standards of European Union.

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µA, mA, A

No. Symbol Meaning

9

Ω,kΩ,MΩ

mV, V

µF nF

o

F

Fahrenheit temperature

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black red

(figure 3)

Warning
To avoid harm to you or damage to the Meter from
electric shock, please do not attempt to measure
voltages higher than 1000V although readings may
be obtained.

The DC Voltage ranges are: 200mV, 2V, 20V, 200V and
1000V.
The AC Voltage ranges are: 2V, 20V, 200V and 1000V

Measurement Operation(1)

A.DC and AC Voltage Measurement (see figure 3)

To measure DC or AC V oltage, connect the Meter as follows:

1. Insert the red test lead into the HzVΩ terminal
and the black test lead into the COM input terminal.

2. Set the rotary switch to an appropriate measurement
position in V or V range.

3. Connect the test leads across with the object to be
measured.
The measured value shows on the display.

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black red

(figure 4)

Warning
Never attempt an in-circuit current measurement
where the open circuit voltage between terminals
and ground is greater than 250V .
If the fuse burns out during measurement, the Meter
may be damaged or the operator may be injured.

Measurement Operation(2)

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Use proper terminals, function, and range for the
measurement. When the test leads are connected
to the current terminals, do not parallel them across
any circuit.

Measurement Operation(3)

The DC Current ranges are:2mA, 200mA, 20A
The AC Current ranges are: 2mA, 200mA and 20A

To measure current, do the following:

1. Turn off power to the circuit. Discharge all high­ voltage capacitors.

2. Insert the red test lead into the A or mA terminal
and the black test lead into the COM terminal.

3. Set the rotary switch to an appropriate measurement
position in A or A range.

4. Break the current path to be tested. Connect the red
test lead to the more positive side of the break and
the black test lead to the more negative side of the
break.

5. Turn on power to the circuit.
The measured value shows on the display.

In consideration of safety, the measure timer for high
current...

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Measurement Operation(4)

Warning
To avoid damage to the Meter or to the devices
under test, disconnect circuit power and discharge
all the high-voltage capacitors before measuring
resistance.

black red

(figure 4)

The resistance ranges are:200Ω, 2kΩ, 20kΩ, 2MΩ
and 20MΩ.

1. Insert the red test lead into the Hz VΩ terminal
and the black test lead into the COM terminal.

2. Set the rotary switch to an appropriate measurement
position in Ω range.

3. Connect the test leads across with the object being
measured.
The measured value shows on the display.

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black red

(figure 6)

Note

l The test leads can add 0.1to 0.2Ω of error to the
resistance measurement. To obtain accurate readings
in low-resistance, short-circuit the input terminals
beforehand and record the reading obtained (called
this reading as X). (X) is the additional resistance from
the test lead. Then use the equation:
measured resistance value (Y) – (X) = accurate readings
of resistance.
l If the input terminal short-circuit reading 0.5,check
the test leads for any looseness or other cause.
l For high resistance (>1MΩ), it may require several
seconds to obtain a stable reading; select short test
leads for stable and precise readings.
l When the resistance is higher than the maximum range
or in open circuit condition, the Meter displays “1”.
l When resistance measurement has been completed,
disconnect the connection between the testing leads
and the circuit under test.

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Warning
To avoid damage to the Meter or to the equipment
under test, disconnect circuit power and discharge
all high-voltage capacitors before measuring diodes.

To avoid personal injury, please do not attempt to
input voltages higher than 60V DC or 30V rms AC.

Use the diode test to check diodes, transistors, and other
semiconductor devices. The diode test sends a current
through the semiconductor junction, and then measures
the voltage drop across the junction. A good silicon junction
drops between 0.5V and 0.8V

To test out a diode out of a circuit, connect the Meter as
follows:

1. Insert the red test lead into the Hz VΩ terminal
and the black test lead into the COM terminal

2. Set the rotary switch to .

3. For forward voltage drop readings on any semiconductor
component, place the red test lead on the component’s
anode and place the black test lead on the component’s
cathode.
The measured value shows on the display.

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l The open-circuit voltage is around 3V.
l When diode testing has been completed, disconnect

the connection between the testing leads and the
circuit under test.

Measurement Operation(7)

black red

(figure 7)

Warning
To avoid personal injury, please do not attempt to
input voltages higher than 60V DC or 30V rms AC.
T o avoid damage to the Meter or to the devices under
test, disconnect circuit power and discharge all the
high-voltage capacitors before testing for continuity.

To test for continuity, connect the Meter as below:

1. Insert the red test lead into Hz VΩ terminal and
the black test lead into the COM terminal.

2. Set the rotary switch to

.

3. Connect the test leads across with the object being
measured.

4. The buzzer does not sound if the resistance of a
circuit under test is >100

Ω

The buzzer sounds continuously if the circuit is in
good condition with resistance value 10Ω.
The measured value shows on the display and the
unit is Ω.

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To avoid personal injury,

F

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value above 10 F.

To avoid personal injury or damage to the meter,

T o ensure the highest level of accuracy, the ambient
temperature of the meter case should be between
64-740F. This is especially true with low temperature
measure ment.

F F

u

F

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F

hFE

To avoid personal injury,

and mA

POWER

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100

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General Specifications

Maximum Voltage or Current between input Terminals and
Ground: According to different functional input protection
value.

l

Fused Protection for
l AmA Input Terminal : 0.5A, 250V fast
type, 5x20mm.
l Maximum Display : 1999,updates 2~3 times/
second.

l Range : Manual ranging.
l Polarity display : Automatically
l Overloading : Display “1”.
l Battery Deficiency : Display “ ”.
l Temperature: Operating: 0oC~40oC (32oF~104oF);

Storage : -10oC~50oC(14oF~122oF)

l Relative Humidity

l Electromagnetic

Compatibility : In a radio field of 1 V/m,
Overall Accuracy = Specified
Accuracy + 5% of Range;
in a radio field of more than
1 V/m, no assigned accuracy
is specified.
l Battery Type : One piece of 9V (NEDA1604
or 6F22 or 006P).

l Dimensions : 7 x 3.5 x 1.5
l Weight : Approx.13.4 OE (including

holster and battery)
l Safety/Compliances : IEC61010 CAT II 1000V,
CATIII 600V overvoltage
and double insulation standard.
l Certificate:

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: 75% @ 0oC~ 30oC; 50%
@ 30oC~40oC

A. DC Voltage

200mV

2V

20V

200V

1000V

0.1mV
1mV

10mV

100mV

1V

Range Resolution

(0.5%+1)

Overload
Protection

Accuracy

250V AC

(0.8%+2)

1000V AC

Remarks:Input Impedance: approx.10MΩ.

B. AC Voltage

2V

20V

200V

1000V

1mV

10mV

100mV

1V

Range Resolution

(0.8%+3)

Overload
Protection

Accuracy

(1.2%+3)

1000V AC

Remarks:

l Input Impedance: approx.10MΩ.
l Frequency response:

40Hz~1kHz< 500V;
40Hz~400Hz > 500V
l Displays effective value of sine wave (mean value
response).

Accuracy Specifications(1)

Accuracy specifications are guaranteed one year.
Operating temperature:18oC~28oC.
Relative humidity: 75%RH.

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Accuracy Specifications(2)

C. DC Current

Remarks:

l At 20A Range:

For continuous measurement 10 seconds and
interval time between 2 measurement greater than
15 minutes.

D. AC Current

Remarks:

l Frequency reaponse: 40Hz~1kHz
l At 20A Range:

For continuous measurement 10 seconds and
interval time between 2 measurement greater than
15 minutes

2mA

200mA

20A

1µA

0.1mA
10mA

Range

Resolution

(0.8%+1)

Overload
Protection

Accuracy

(2%+5)

(1.5%+1)

Un-Fused

2mA

200mA

20A

1µA

0.1mA

10mA

Range

Resolution

(1.0%+3)

Overload
Protection

Accuracy

Un-Fused

(1.8%+3)

(3.0%+5)

Fuse 0.5A, 250V,
fast type, 5x20mm

CE Version:Fuse

0.5A, 250V, fast
type, 5x20mm

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100

H. Capacitance

Accuracy Specifications(4)

±(5.0%+4)

When it is 40µF: the obtained

reading is only for reference

2nF 1pF

200nF 0.1nF
100µF 0.1µF

I. Temperature

Range Resolution

Accuracy

(4.0%+3)

Range Resolution

Accuracy

0~400oF (1%+3)

7

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FF

F

F

F

1

440

Accuracy Specifications(5)

J. Transistor test

Range Resolution

Accuracy±(a% reading + b digits)

hFE 1β Vce•3V Ibo•10µA 1000βMAX

K. Frequency

Range Resolution

Overload
Protection

Accuracy

2kHz 1Hz
20kHz 10Hz

±(1.5%+5) 250V AC

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Maintenance(1)

This section provides basic maintenance information
including battery and fuse replacement instruction.

Warning
Do not attempt to repair or service your Meter unless
you are qualified to do so and have the relevant
calibration, performance test, and service information.
To avoid electrical shock or damage to the Meter, do
not get water inside the case.

A. General Service

l Periodically wipe the case with damp cloth and mild
detergent. Do not use chemical solvent.

l To clean the terminals with cotton bar with detergent,
as dirt or moisture in the terminals can affect readings.

l Turn the Meter off when it is not in use and take out
the battery when not using for a long time.

l Do not store the Meter in place of humidity, high
temperature, explosive, inflammable and strong
magnetic field

B. Replacing the fuse (see figure 10)

Warning
To avoid electrical shock, arc blast, personal
injury or damage to the Meter, use specified fuses
ONLY in accordance with the following procedure.

( figure 10)

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To replace the Meter’s fuse:

1. Turn the Meter off and remove all connections from
the terminals.

2. Remove the holster from the Meter.

3. Remove the 3 screws from the case bottom, and
separate the case top from the case bottom.

4. Remove the fuse by gently prying one end loose,
then take out the fuse from its bracket.

5. Install ONL Y replacement fuses with the identical type
and specification and make sure the fuse is fixed
firmly in the bracket.
Fuse: 0.5A, 250V, fast type,φ5x20mm

6. Rejoin the case bottom and case top, and reinstall
the 3 screws and holster.

An open fuse is always the result of improper operation.

Maintenance(2)

C.Replacing the Battery (see figure 10)

To replace the Meter’s battery:

1. Turn the Meter power off and remove all connections
from the terminals.

2. Remove the holster from the Meter.

3. Remove the 3 screws from the case bottom, and
separate the case top from the case bottom.

4. Remove the battery from the battery connector.

5. Replace with a new 9V battery (NEDA1604, 6F22
or 006P).

6. Rejoin the case bottom and case top, and reinstall
the 3 screws and the holster.

Warning
To avoid false readings, which could lead to possible
electric shock or personal injury, replace the battery
as soon as the battery indicator “ ” appears.

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** END **

This operating manual is subject to change without notice.

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Copyright 2005 Tenma Test Equipment.

All rights reserved.

Tenma Test Equipment
405 S. Pioneer Blvd.
Springboro,Ohio 45066
www.tenma.com

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