UNI-T UT50D Operating Manual

1

Overview
Unpacking Inspection
Safety Information
Rules For Safe Operation
International Electrical Symbols
The Meter Structure
Functional Buttons
Display Symbols
Measurement Operation
A. DC Voltage Measurement
B. AC Voltage Measurement
C. DC Current Measurement
D. AC Current Measurement
E. Measuring Resistance
F. Inductance Measurement
G. Capacitance Measurement
H. Temperature Measurement
I. Measuring Diodes & Continuity
Sleep Mode
Turning on the Auto Display Backlight
General Specifications
Accuracy Specifications
A. DC Voltage
B. AC Voltage
C. DC Current
D. AC Current
E. Resistance Test
F. Inductance
G. Capacitance
H. Temperature
I. Diodes and Continuity Test

Table of Contents

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6
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9

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34

Maintenance
A. General Service
B. Replacing the Battery
C. Replacing the Fuses

Model UT50D: OPERATING MANUAL

2

Digital Multimeters Model UT50D (hereafter referred to
as “the Meter”) is a 3 1/2 digits with steady operations,
fashionable structure and highly reliable hand-held
measuring instrument. The Meter uses large scale of
integrated circuit with double integrated A/D converter
as its core and has full range overload protection. The
Meter not only can measure AC/DC Voltage, AC/DC
Current, Resistance, Capacitance, Temperature,
Inductance, Diodes and Continuity, but also has Data
Hold, Full Icon Display and Sleep Mode features.

The Meter adopted advanced “co-injection” technique in
order to provide sufficient insulation and anti-shaking.
In addition, the Automatic Display Backlight feature
enables user to work in a dim condition.

Warning
To avoid electric shock or personal injury, read the
“Safety Information” and “Rules for Safety Operation”
carefully before using the Meter.

Model UT50D: OPERATING MANUAL

3

1 English Operating Manual 1 piece
2 Test Lead 1 pair
3 Test Clip 1 piece
4 Point Contact Temperature Probe
5 9V Battery (NEDA 1604, 6F22 or 009P)
(installed inside the Meter)

1 piece
1 piece

Item

Description

Qty

In the event you find any missing or damage, please
contact your dealer immediately.

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Model UT50D: OPERATING MANUAL

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, POR TABLE 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 on.

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

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Model UT50D: OPERATING MANUAL

Rules For Safe Operation (1)

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.
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.
Do not apply more than the rated voltage, as
marked on the Meter, between the terminals or
between any terminal and grounding.
The rotary switch should be placed in the right
position and no any changeover of range shall
be made during measurement is conducted to
prevent damage of the Meter.
When the Meter working at an effective voltage
over 60V in DC or 30V rms in AC, special care
should be taken for there is danger of electric
shock.
Use the proper terminals, function, and range
for your measurements.
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.
When using the test leads, keep your fingers
behind the finger guards.

6

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:

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Model UT50D: OPERATING MANUAL

Rules For Safe Operation (2)

Disconnect circuit power and discharge all high

-voltage capacitors before testing resistance,
continuity, diodes, capacitance or current.
Before measuring current, check the Meter’s
fuses and turn off power to the circuit before
connecting the Meter to the circuit.
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.
Remove test leads, test clips and temperature
probe from the Meter and turn the Meter power
off before opening the Meter case.
When servicing the Meter, use only the same
model number or identical electrical specifications
replacement parts.
The internal circuit of the Meter shall not be
altered at will to avoid damage of the Meter and
any accident.
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.
The Meter is suitable for indoor use.
Turn the Meter power off when it is not in use
and take out the battery when not using for a long
time.
Constantly check the battery as it may leak when
it has been using for some time, replace the battery
as soon as leaking appears. A leaking battery will
damage the Meter.

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Model UT50D: OPERATING MANUAL

International Electrical Symbols

AC (Alternating Current).
DC (Direct Current).
Grounding.
Double Insulated.
Deficiency of Built-In Battery.
Warning. Refer to the Operating Manual.

Conforms to Standards of European Union.

Diode.
AC or DC.

Fuse.
Continuity Test.

Model UT50D: OPERATING MANUAL

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9

(figure 1)

The Meter Structure (see figure 1)

1. LCD Display

2. Data Hold Button.

3. Rotary Switch

4. Other Input Terminals

5. COM Input Terminal

6. 20A Input Terminal

7. mA Input terminal

8. Power

Model UT50D: OPERATING MANUAL

Button Operation Performed

Turn the Meter on and off.
l Press down the POWER to turn
on the Meter.
l Press up the POWER to turn off
the Meter.

HOLD

(Blue Button)

l Press HOLD once to enter hold
mode.
l Press HOLD again to exit hold
mode.
l In Hold mode, is displayed and
the present value is shown.

POWER

(Yellow Button)

Functional Buttons

Below table indicated for information about the functional
button operations

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(figure 2)

Display Symbols(1) (see figure 2)

No. Symbol Meaning

1

Dangerous Voltages.

2

The battery is low.

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.

3

Indicator for AC voltage or
current.The displayed value is the
mean value.

4

Indicates negative reading.

5

Test of diode.

6

Data hold is active.

7

The continuity buzzer is on.

8

Centigrade temperature

o

C

o

F

9

Fahrenheit temperature

10

V: Volts. The unit of voltage.
mV: Millivolt. 1 x 10-3 or 0.001 volts.

mV, V

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No. Symbol Meaning

12

mH,H

13

14

H: Henry. The unit of Inductance.
mH: Millihenry. 1 x 10

-3

or 0.001

henry.

Display Symbols(2) (see figure 2)

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Model UT50D: OPERATING MANUAL

Make sure the Sleep Mode is not on if you found
there is no display on the LCD after turning on the
Meter.
Make sure the Low Battery Display is not on,
otherwise false readings may be provided.

Pay extra attention to the

symbol which is located
besides the input terminals of the Meter before
carrying out measeurement.

l

l
l

(figure 3)

The DC Voltage ranges are: 200mV, 2V, 20V, 200V and
1000V. To measure DC voltage, connect the Meter as
follows:

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Model UT50D: OPERATING MANUAL

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Model UT50D: OPERATING MANUAL

l If the value of voltage to be measured is unknown,
use the maximum measurement position (1000V)
and reduce the range step by step until a satisfactory
reading is obtained.

l The LCD displays “1” indicating the existing selected
range is overloaded, it is required to select a higher
range in order to obtain a correct reading.
l In each range, the Meter has an input impedance of
approx. 10M . This loading effect can cause
measurement errors in high impedance circuits. If the
circuit impedance is less than or equal to 10k , the
error is negligible (0.1% or less).
l When DC voltage measurement has been completed,
disconnect the connection between the testing leads
and the circuit under test.

1. Insert the red test lead into thei V nput terminal
and the black test lead into the COM input terminal.

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

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

The AC voltage measurement has 4 measurement
positions on the rotary switch: 2V, 20V, 200V and 750V
To measure AC Voltage, connect the Meter as follows:

l If the value of voltage to be measured is unknown,
use the maximum measurement position (750V) and
reduce the range step by step until a satisfactory
reading is obtained.
l The LCD displays “1” indicating the existing selected
range is overloaded, it is required to select a higher
range in order to obtain a correct reading.
l In each range, the Meter has an input impedance of
approx. 10M . This loading effect can cause
measurement errors in high impedance circuits. If the
circuit impedance is less than or equal to 10k , the
error is negligible (0.1% or less).
l When AC voltage measurement has been completed,
disconnect the connection between the testing leads
and the circuit under test.

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

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

3. Connect the test leads across with the object being
measured.
The measured value shows on the display, which is
effective value of sine wave (mean value response).

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Model UT50D: OPERATING MANUAL

( figure 4)

The DC current measurement has 3 measurement
positions on the rotary switch: 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 mA or 20A terminal
and the black test lead into the COM terminal.

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

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17

Measurement Operation(5)

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.

l If the value of current to be measured is unknown,
use the maximum measurement position (20A) and
20A terminal, and reduce the range step by step until
a satisfactory reading is obtained.
l When current measurement has been completed,
disconnect the connection between the testing leads
and the circuit under test.

( figure 4)

Model UT50D: OPERATING MANUAL

Measurement Operation(6)

The AC current measurement has 3 measurement positions
on the rotary switch: 20mA, 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 mA or 20A terminal and
the black test lead into the COM terminal.

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

l If the value of current to be measured is unknown, use
the maximum measurement position (20A) and 20A
terminal and reduce the range step by step until a
satisfactory reading is obtained.
l When current measurement has been completed,
disconnect the connection between the testing leads
and the circuit under test.

Model UT50D: OPERATING MANUAL

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Measurement Operation(7)

( figure 5)

The resistance ranges are:200 ,2k ,200k ,2M ,and
20M .
To measure resistance, connect the Meter as follows:

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

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

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

l The test leads can add 0.1 to0.3 of error when
measuring low resistance, that is the range of 200 .

To obtain precision readings in low-resistance, use

the following equation:

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Precision readings of resistance = Measurement
displayed reading minus the short circuit value of red
and black test lead.
l For high resistance (>1M ), it is normal taking several
seconds to obtain a stable reading.
l When there is no input, for example 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.

Measurement Operation(8)

( figure 6)

Inductance measurement has 4 measurement positions
on the rotary switch: 2mH, 20mH, 200mH and 20H.

To test for Inductance, connect the Meter as below:

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Model UT50D: OPERATING MANUAL

1. According to the size of the tested object’s leads,
insert multi-purpose socket or test clip into the mA
and V terminal.

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

3. Insert the tested object into the corresponding jack
of the multi-purpose socket or connect the test clip
to the object being measured.
The measured value shows on the display.

Measurement Operation(9)

l If the value of inductance to be measured is unknown,
use the maximum measurement position, and reduce
the range step by step until a satisfactory reading is
obtained.
l When inductance testing has been completed, remove
the multi-purpose socket or test clip from the input
terminal, and remove multi-purpose socket or test clip
away from the input terminal of the Meter.

( figure 7)

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Model UT50D: OPERATING MANUAL

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Model UT50D: OPERATING MANUAL

Measurement Operation(10)

l For testing the capacitor with polarity, connect the
red test lead or test clip to anode & black test lead
or test clip to cathode
l When the tested capacitor is shorted or the capacitor
value is overloaded, the LCD display “1”.
l To minimize the measurement error caused by the
distributed capacitor, the testing lead or testing clip
should be as short as possible.
l To ensure precision especially when measuring small
capacitance 200nF range, the correct reading is as
follows:
Measurement displayed reading minus the Meter’s
open circuit displayed value.
l It is normal to take a while for zeroing when changing
over the measurement range. This process will not
affect the accuracy of the final readings obtained.

30V

Measurement Operation(11)

( figure 8)

The temperature measurement range is from -40oC ~1000oC.
To measure temperature, connect the Meter as follows:

1. Insert the red temperature into the V terminal
and the black temperature probe into the COM terminal.

2. Set the rotary switch to .

3. Place the temperature probe to the object being
measured.
The measured value shows on the display.

l The Meter automatically displays the temperature
value inside the Meter when there is no temperature
probe connection.
l The included temperature probe can only be measured
up to 250 . For any mesaurement higher than that,
the rod type temperature probe must be used instead.

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Model UT50D: OPERATING MANUAL

l When temperature measeuremnet has been completed,
disconnect the connection between the testing leads
and te circuit under test.

Measurement Operation(12)

( figure 9)

Testing Diodes
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 V terminal and
the black test lead into the COM terminal.

Model UT50D: OPERATING MANUAL

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25

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.

Measurement Operation(13)

l In a circuit, a good diode should still produce a forward
voltage drop reading of 0.5V to 0.8V; however; the
reverse voltage drop reading can vary depending on
the resistance of other pathways between the probe
tips.
l Connect the test leads to the proper terminals as
said above to avoid error display . The LCD will display
“1” indicating open-circuit for wrong connection.The
unit of diode is Volt (V), displaying the positive­ connection voltage-drop value.
l When diode testing has been completed, disconnect
the connection between the testing leads and the
circuit under test.

To test for continuity, connect the Meter as below:

1. Insert the red test lead into V 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.
The buzzer sounds if the resistance of a circuit under
test is less than 70
The LCD displays the resistance value of a circuit
under test.

Model UT50D: OPERATING MANUAL

l The LCD display “1” indicating the circuit being tested
is open.
l When continuity testing has been completed, disconnect
the connection between the testing leads and the circuit
under test.

Measurement Operation(14)

Model UT50D: OPERATING MANUAL

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Model UT50D: OPERATING MANUAL

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Sleep Mode

To preserve battery life, the Meter automatically turns off
if you do not turn the rotary switch or press any button
for around 8 minutes. At that time, the Meter consumes
around 10µA current.
The Meter can be activated by pressing the POWER two
times.

Turning on the Auto Display Backlight

The Meter has a built-in sensor. Therefore the Display
Backlight turns on and off automatically depending on
the brightness of the environment. In a dim condition,
the Display Backlight turns on automatically while in a
bright condition, the Display Backlight turns off automatically.

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Model UT50D: OPERATING MANUAL

l Maximum voltage
between any Terminals
and Grounding :1000V rms.

l

Fused Protection
for mA Input Terminal :0.5A, 250V fast type,
5x20mm.

l

Fused Protection
for 20A Input Terminal :Un-fused.

l Range :Manual ranging.
l Maximum Display :1999.
l Mesaurement Speed :Updates 2~3 times/second.
l Temperature:

Operating:0oC~40oC(32oF~104oF)

Storage: -10oC~50oC(14oF~122oF).
l Relative Humidity : 75% @ 0oC~30oC;
50%@31oC~40oC.

l Altitude: Operating :2000m; Storage: 10000m.
l Battery Type :9V NEDA1604 or 6F22 or

006P.

l Battery Deficiency :Display “ ”.
l Data Holding :Display “ H ”
l Negative reading :Display “

“

l Overloading :Display “1”.
l Dimensions (HxWxL) :165x80x38.3mm.
l Weight : Approx.275g (battery

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

A. DC Voltage

200mV

2V

20V

200V

1000V

Range Resolution

(0.5%+1)

Overload Protection

Accuracy

250V DC or AC rms.

(0.8%+2)

0.1mV

0.001V

0.01V

0.1V
1V

1000V DC /

750V ACrms.

B. AC Voltage

Range Resolution

(0.8%+3)

Overload ProtectionAccuracy

2V

20V
200V
750V

0.001V

0.01V

0.1V
1V

(1.2%+3)

250V DC or AC rms.

1000V DC /

750V ACrms.

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Model UT50D: OPERATING MANUAL

Accuracy: (a% reading + b digits)
Operating temperature:23oC

5oC.

Relative humidity:<75%.
Temperature coefficient: 0.1 x (specified accuracy) / 1oC.

guarantee for 1 year.

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Model UT50D: OPERATING MANUAL

Remarks:

l At 20A Range: For continuous measurement

10

seconds and interval not less than 15 minutes.

l Measurement voltage drop: Full range at 200mV.

D. AC Current

Remarks:

l At 20A Range: For continuous measurement

10

seconds and interval not less than 15 minutes.

l Measurement voltage drop: Full range at 200mV.
l Frequency reaponse: 40Hz~400Hz
l Display effective value of sine wave (mean value

response).

Range Resolution Overload ProtectionAccuracy

20mA

200mA

20A

0.01mA

0.1mA
10mA

0.5A. 250V fast type
fuse, 5x20mm

(1%+3)

Un-Fused

(1.8%+3)

(3%+5)

C. DC Current

Range Resolution Overload ProtectionAccuracy

2mA

200mA

20A

0.001mA

0.1mA
10mA

0.5A. 250V fast type
fuse, 5x20mm

(0.8%+1)

(2%+5)

Un-Fused

(1.5%+1)

E. Resistance Test

Remarks:

Range Resolution

Overload
Protection

Accuracy

(0.8%+3)

250V rms

(0.8%+1)

(1%+5)

Range Resolution Overload ProtectionAccuracy

2mH

20mH

200mH

20H

250V rms

10pF

100pF

1nF

100nF

Range Resolution

Overload Protection

Accuracy

250V rms

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Model UT50D: OPERATING MANUAL

l At 200 range, short circuit the test lead first to
display the test lead resistance value. During
measurement, subtract the test lead resistance value
from the displayed reading to obtain the accurate
reading.

(2%+10)

(3%+10)

(2.5%+5)

(5%+4)

H. Temperature

Range

Resolution

(3%+3)

Overload
Protection

Accuracy

-40oC~0oC

0oC~400oC

400oC~1000oC

(1%+3)

1oC

2.5%

250V rms

Open circuit
voltage approx.

2.8V

250V DC

or AC

<70 buzzer
beeps
continuously

Diodes

Continuity

Test

1mV

Model UT50D: OPERATING MANUAL

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I. Diodes and Continuity Test

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Model UT50D: OPERATING MANUAL

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

Screw

Fuse

Fuse

Rubber foot

( figure 10)

Model UT50D: OPERATING MANUAL

34

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.

To replace battery:

1. Disconnect the connection between the testing leads
and the circuit under test, and remove the testing
leads away from the input terminals of the Meter.

2. Turn the Meter off

3. Remove the rubber feet and screws from the battery
compartment, and separate the battery compartment
from the case bottom

4. Remove the battery from the battery compartment.

5. Replace the battery with a new 9V battery (NEDA
1604 or 6F22 or 006P).

6. Rejoin the battery compartment and the case bottom,
and install the screw and rubber feet.

Screw

Fuse

Fuse

Rubber foot

( figure 10)

~ END ~

This operating manual is subject to change without notice.

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Model UT50D: OPERATING MANUAL

To replace the Meter’s fuse:

1. Disconnect the connection between the testing leads
and the circuit under test, and remove the testing
leads away from the input terminals of the Meter.

2. Turn the Meter off.

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

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

5. Install ONL Y replacement fuses with the identical type
and specification as follows and make sure the fuse
is fixed firmly in the bracket.

0.5A. 250V fast type fuse, 5x20mm

6. Rejoin the case bottom and the case top, and install
the screw and rubber feet

Replacement of fuses is seldom required. Burning
of a fuse always results from the improper operation.

Copyright 2003 Uni-Trend Group Limited.

All rights reserved.
Manufacturer:

Uni-Trend Technology (Dongguan) Limited
Dong Fang Da Dao
Bei Shan Dong Fang Industrial Development District
Hu Men Town, Dongguan City
Guang Dong Province
China
Postal Code: 523 925

Headquarters:
Uni-Trend Group Limited
Rm901, 9/F, Nanyang Plaza
57 Hung To Road
Kwun Tong
Kowloon, Hong Kong
Tel: [phone]
Fax: [phone]
Email: [e-mail]
http://www.uni-trend.com

Model UT50D: OPERATING MANUAL

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