UNI-T ut81b, ut81a Operating Manual

JSP, s.r.o., Raisova 547, 506 01 Jičín, Czech Republic
Phone: [phone], Fax: [phone], e-mail: [e-mail]

www.jsp.cz

JSP Industrial Controls

Model UT81A/B

OPERATING MANUAL

Chapter Title Page

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Model UT81A/B: OPERATING MANUAL

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Table of Contents

1 Before You Start

Overview
Unpacking Inspection
Safety Information
Rules For Safe Operation
International Electrical Symbols

2 Using The Testing Tool

Reading the screen
The Meter Structure
Functional Buttons

3 Making Measurements

A. Scope Mode
i. Setting up the Sleep Mode, Contrast, Beep
ii. ACV, DCV, Hz, ACV and DCA Range
iii. Trigger function
iv. Waveform data save and recall
B. Digital Multimeter Mode
i. Measuring Voltages
ii. Measuring Currents
iii. Measuring Resistance
iv. Testing Diodes
v. Testing for Continuity
vi. Measuring Frequency / Duty Cycle

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Chapter Title Page

Table of Contents

A.
B.
C.
D.
E.
F.
G.

DC Voltage
AC Voltage
DC Current
AC Current
Resistance
Diode Test
Continuity Test

vii. Measuring Capacitance

4 Using Software
5 Maintenance The Test Tool

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

6 Specifications

Safety and Compliances
Physical Specifications
General Specifications (Digital Multimeter)
General Specifications (Scope)
Feature Summary
Basic Specifications (Digital Multimeter)
Basic Specifications (Scope)
Detailed Accuracy Specifications

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Chapter Title Page

Table of Contents

H. Frequency and Duty Cycle %
I. Capacitance

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Table Title Page

List of Tables

1-1 Unpacking Inspection
1-2 International Electrical Symbols
2-1 Reading the Screen
2-2 Functional Buttons

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Figure Title Page

List of Tables

2-1 Meter Structure
2-2 Functional Buttons
3-1 Waveform Display
3-2 Voltages Measurement
3-3 µA Range Measurement
3-4 mA Range Measurement
3-5 10A Range Measurement
3-6 Resistance Measurement
3-7 Diode Test
3-8 Continuity Test
3-9 Frequency / Duty Cycle Measurement
3-10 Capacitance Measurement
5-1 Fuse Replacement
5-2 Battery Replacement

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Model UT81A/B: OPERATING MANUAL

Overview

This Operating Manual covers information on safety
and cautions. Please read the relevant information
carefully and observe all the Warnings and Notes
strictly.

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

Scope Digital Multimeter UT81A/B (hereafter referred
to as “the Meter”) is a 3999 counts and 3 3/4 digits
adopting digital control techique with both waveform
and multimeter all in one.

Scope mode is a complete intelligent measurement
system including signal input, sampling, data process,
auto search and waveform save and recall. It has

Chapter 1

Before You Start

bandwidth UT81A:2MHz,UT81B:8MHz, real-time sample
rate 40MS/s with peak rate sampling process can catch
up pulse industrial signal. It can measure AC/DC engine,
transducer, circuit, control, UPS and industrial
equipments. It is an ideal tools in professional repairing
industries.

Digital Multimeter mode can measure AC voltage and
current, DC voltage and current, Resistance,
Capacitance, Frequency, Duty Cycle, Diodes and
Continuity.

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Item Description Qty

Model UT81A/B: OPERATING MANUAL

Unpacking Inspection

Open the package case and take out the Meter. Check the items shown on Table 1-1 carefully to see any missing
or damaged part:

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

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2
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5
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English Operating Manual
USB interface cable
CD-ROM (Installation Guide & Computer Interface Software)
Test Lead
Alligator Clip
Power Adaptor

1.5V Batteries (R6)
Carrying bag
Scope Probe (available at extra cost)
BNC probe (available at extra cost)

1 piece
1 piece
1 piece
1 pair
1 piece
1 piece
4 pieces
1 piece
1 piece

Table 1-1. Unpacking Inspection

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Model UT81A/B: OPERATING MANUAL

Safety Information

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

CA T.II: Local level, appliance, PORT ABLE EQUIPMENT
etc., with smaller transient overvoltages than CAT. III
CA T. III: Distribution level, fixed installation, with smaller
transient overvoltage 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 may 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.

Warning

International electrical symbols used on the Meter and
in this Operating Manual are explained on page 10.

Rules For Safe Operation

T o 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:

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 1000V rms between
any terminal and grounding to avoid electric

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Model UT81A/B: OPERATING MANUAL

shock or damages to the Meter.
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 42V 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.
Disconnect circuit power and discharge all high­voltage capacitors before testing resistance,
continuity, diodes.
Before measuring current, check the Meter’s
fuses and turn off power to the circuit before

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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.
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.
T urn the Meter off when it is not in us e 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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International Electrical Symbols

AC or DC
DC Measurement
AC Measurement
Continuity Test
Diode
Grounding
Double Insulated
Warning. Refer to the Operating Manual
Deficiency of Built-In Battery
Conforms to Standards of European Union

Symbols used on the Meter and in this manual are
explained in Table1-2.

Table 1-2. International Electrical Symbols

l Under the influence of Radiated Radio-Frequency

Electromagnetic Field phenomenon, the captioned
model have a 20% measurement error, it will be
back to normal when the interference is removed.

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Chapter 2

Using the T esting Tool

Reading the Screen

Description

The degree of contrast
Sleep mode time
Display backlight
Beeper on and off
Confirm
Increase
Decrease
Waveform moves up
Waveform moves down
Increase a range

The screen displays the menu that provides the following
choices available:

Table 2-1. Reading the Screen

Description

Decrease a range
Increase a time base
Decrease a time base
Waveform moves right
Waveform moves left
Trigger moves up
Trigger moves down
Trigger slope adjustment
Auto trigger mode
Normal trigger mode
Single trigger mode

Display

Contrast
Auto Off
BK Light
BEEP
ENTER

MOVE
MOVE
RANG

Display

RANG
BASE
BASE
BASE >
BASE <
TRIG
TRIG
SLOP
AUTO
NORM
SHOT

Table 2-1. Reading the Screen

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Figure 2-1. Meter Structure

The Meter Structure

The Figure 2-1 shows the Meter structure.

1. USB Terminals

2. LCD Display

3. Functional Buttons

4. Rotary Switch

5. Power adaptor Input Terminals

6. 10A Input Terminal

7. mAµA Input Terminals

8. COM Input Terminal

9. Other Input Terminals

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Model UT81A/B: OPERATING MANUAL

Figure 2-2. Functional Buttons

Table 2-2. Functional Buttons

Description

Software functional buttons, details
please refer to the below.
Under scope mode, Press Range
button to switch between DC and AC
measurement
Under scope mode, press Time button
to set the X-axis of time base.
Under scope mode, press Trig button
to change the trigger mode.
In multimeter mode: Press Auto button
to enter autoranging mode when
measuring resistance, voltage and
current. This button is invalid when
measuring capacitance, diode, continuity
buzzer and capacitance.
In scope mode: Press Auto button to
set the amplitude and time base to auto.

Buttons
F1, F2,
F3 and F4
Range

Time

Trig

Auto

Functional Buttons

The buttons activate features that augment the function
selected with the rotary switch. The buttons are shown
in Table 2-2.

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Model UT81A/B: OPERATING MANUAL

Table 2-2. Functional Buttons

Buttons

Mode

Set

Save/Call

Hold

Description

To switch between waveform display
(scope mode) and digital reading
(multimeter mode). This button is only
valid when under voltage, frequency,
currents mode.
Press Set button to set the auto power
off, backlight, contrast and beep
Under scope mode, press Save/Cal to
store and recall data.
Press Hold button to enter or exit hold
mode.

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Chapter 3

Making Measurement

Introduction

Chapter 3 explains how to make measurements.
You could turn the Meter off by turning to OFF position

or set up the sleep mode from 1-30 minutes. Please
must ensure the Meter is not under sleep mode if you
turn the Meter on but without display.

To avoid false readings, which could lead to possible
electric shock or personal injury , replace the battery as

soon as the battery indicator “

” appears.

Based on the working environment to set up sleep
mode, contrast, beep
Press Set button to set the auto power off, display
backlight, contrast and beep
Auto off Bk Light Contrast Beep
F1 F2 F3 F4

F1: Set auto power off time
Auto off 15 ENTER
F1 F2 F3 F4
The time level is from OFF, 1 to 30 minutes. Press F4
to confirm, save and return. Press functional button to
exit and the setting remains unchanged.

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Model UT81A/B: OPERATING MANUAL

F2: Set the Display Backlight
BK Light 15 ENTER
F1 F2 F3 F4

The brightness level from 0 to 31. Press F4 to
confirm, save and return. Press functional buttons
to exit, the setting is kept, but will not save. The
setting will be lost after power off.

F3: Set the LCD contrast

Contrast 15 ENTER

F1 F2 F3 F4

The contrast level from 0 to 31. Press F4 to confirm,
save and return. Press functional buttons to exit,
the setting is kept, but will not save. The setting will
be lost after power off.

F4: Set the beeps features, it can only be used under

resistance, diode and continuity measurement.

Beep ON OFF ENTER
F1 F2 F3 F4

F2 : to turn the beep on
F3 : to turn the beep off
F4 : to confirm , save and return

Press functional buttons to exit, the setting is kept, but

will not save. The setting will be lost after power off.

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Figure 3-1. Waveform Display

Turn the rotary switch to ACV, DCV, Hz, ACA or DCA
range, the Meter displays digital reading (Multimeter
mode). Press Mode to switch to waveform display
(scope mode) as below Figure 4. When entering scope
mode, time base is auto trace, the amplitude is manual
set, you may need to re-set them. You could set the
trigger level as well if it is needed. Details of
measurement operation of ACV, DC, Hz, ACA or DCA
can be seen from B. Digital Multimeter Mode:

Press Range to switch between DC and AC
measurement.
When the frequency and amplitude of a waveform
is unknown, press Auto :

When the amplitude is set to auto, the amplitude
indicator will be shown white text in black
background. When the amplitude is set to manual,
the amplitude indicator will be shown black text
in white background.
When the time base is set to auto, the time base
indicator will be shown white text in black
background. When the time base is set to manual
trace, the time base indicator will be shown black
text in white background.
When the time base is between 20ms - 100ns, it
is possible to set the auto. When the time base
is between 50ms - 5s, the auto feature will be in
valid.

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Model UT81A/B: OPERATING MANUAL

Y -axis adjustment: Press Range button under scope
mode, the corresponding functional button:
Move Move Rang Rang
F1 F2 F3 F4

F1: move up the waveform
F2: move down the waveform
F3: go up range
F4: go down a range

The auto set feature will be off when changing the
measurement mode

Press Time button under scope mode, the
corresponding functional button:
Base Base Base < Base >
F1 F2 F3 F4

F1: increase the number of periods
F2: decrease the number of periods.
F3: trigger point move left
F4: trigger point right move

The auto set feature will be off when changing the
measurement mode.

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Model UT81A/B: OPERATING MANUAL

Press Trig button under scope mode, the
corresponding function buttons:
Trig T rig Auto/Norm/Shot Slop Rrise/Fall
F1 F2 F3 F4

F1: move the trigger level up
F2: move the trigger level down
F3: select the trigger mode: auto, normal or single
F4: slope adjustment: rise or fall

iv. Waveform data save and recall
Press Save/Call button under scope mode, the

corresponding functional buttons:
Save/Call 1 Enter
F1 F2 F3 F4

F1: save or recall
F2 and F3: select location (location from 0-9, total

10 location)
F4: confirm

When saving the data, it will overwrite the current
data in the location no matter that location has data
or not.
If you recall the location has no data, the meter will
appear error message, you need to press HOLD
button to continue measurement,
If you recall the location has data, it will save the
current setting and display the data, the LCD top left
shows REV to indicate recalling mode is on. Press
HOLD button to return to working mode and continue
measurement. You could continue recalling under
recall mode or save the data.
Recall mode can be used under any scope mode.
For example, it is possible to recall the waveform or
data saved from voltage or frequency mode when
the meter is under current measurement mode.
Recall mode can be worked under any waveform
mode. For example: the Meter is at current mode
but recalling the waveform or data which are saved
under voltage or frequency mode. The Meter must

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Model UT81A/B: OPERATING MANUAL

be returned to working mode to carry out measurement.

In order to have more accurate waveform, user can
buy an optional BNC probe and scope probe to decrease
signal attenuates. The scope probe directly connect
to the BNC probe.

When measuring voltage and frequency signal, connect
the BNC black probe to the COM input terminal and
the red probe to the voltage terminal.

When measuring current signal, connect BNC black
probe to the COM terminal and the red probe to mA
terminal.

Don’t connect the BNC probe to the 10A terminal.

B. Digital Multimeter Mode

Warning

T o avoid harms to you or damages to the Meter
from electric shock, please do not attempt to
measure voltages higher than DC 1000V, AC
750V, although readings may be obtained.

To measure voltages, set up the Meter as Figure 3­2 and do the following:

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 V .

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

4. The measured value shows on the display.

5. Press MODE button to toggle between Multimeter
mode and Scope mode.

6. Press F1 to toggle between AC and DC voltage
measurement.

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Model UT81A/B: OPERATING MANUAL

Figure 3-2. Voltages Measurement

When measuring voltage, the corresponding functional
buttons
AC / DC REL Rang Rang
F1 F2 F3 F4

F1: toggle between AC or DC
F2: relative mode (REL will be displayed at the right
bottom of the LCD when it is on)
F3: select a range up
F4: select a range down

After changing the measurement mode, the
autoranging will be off automatically and the AUTO
will be disappeared at the bottom left of the LCD.
When voltage measurement has been completed,
disconnect the connection between the testing
leads and the circuit under test and remove testing
leads away from the input terminals of the Meter.

Note:

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Model UT81A/B: OPERATING MANUAL

If the fuse burns out during measurement, the Meter

may be damaged or the operator himself may be

hurt.

To avoid possible damage to the Meter or to the

equipment under test, check the Meter’s fuses

before measuring current. Use proper terminals,

function, and range for the measurement. Never

place the testing leads in parallel with any circuit

or component when the leads are plugged into the

current terminals.

Turn off power to the circuit before test leads are

connected in series to the return circuit to be tested.

Warning

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Model UT81A/B: OPERATING MANUAL

Figure 3-3. µA Range Measurement

To measure ACµA or DCµA currents, set up the
Meter as Figure 3-3 and proceed as follows:

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

2. Set the rotary switch to µA

.

3. Connect the test lead in series with the return circuit
to be tested.

4. The measured value shows on the display.

5. Press MODE button to toggle between Multimeter
mode and Scope mode.

6. Press F1 to toggle between AC and DC current
measurement.

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Model UT81A/B: OPERATING MANUAL

Figure 3-4. mA Range Measurement

To measure ACmA or DcmA currents, set up the
Meter as Figure 3-4 and proceed as follows:

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

2. Set the rotary switch to mA .

3. Connect the test lead in series with the return circuit
to be tested.

4. The measured value shows on the display.

5. Press MODE button to toggle between Multimeter
mode and Scope mode.

6. Press F1 to toggle between AC and DC current
measurement.

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Model UT81A/B: OPERATING MANUAL

Figure 3-5. 10A Range Measurement

To measure AC 10A or DC 10A currents, set up
the Meter as Figure 3-5 and proceed as follows:

1. Insert the red test lead into the 10A terminal and
black test lead into the COM terminal.

2. Set the rotary switch to A .

3. Connect the test lead in series with the return circuit
to be tested.

4. The measured value shows on the display.

5. Press MODE button to toggle between Multimeter
mode and Scope mode.

6. Press F1 to toggle between AC and DC current
measurement.

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Model UT81A/B: OPERATING MANUAL

NoteWhen measuring current, the corresponding functional

buttons:
AC / DC REL Rang Rang

F1 F2 F3 F4

F1: toggle between AC or DC
F2: relative mode (REL will be displayed at the right
bottom of the LCD when it is on)
F3: select a range up
F4: select a range down

After changing the measurement mode, the
autoranging will be off automatically and the AUTO
will be disappeared at the bottom left of the LCD.
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.
When the measured current is 5A, continuous
measurement is allowed.
When the measured current is between 5A-10A,
continuous measurement 10 seconds and interval
more than 15 minutes.
When current measurement has been completed,
disconnect the connection between the testing leads
and the circuit under test and remove testing leads
away from the input terminals of the Meter.

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Model UT81A/B: OPERATING MANUAL

Figure 3-6. Resistance Measurement

Warning

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

To measure resistance, set up the Meter as shown in
Figure 3-6 and follow the following procedure:

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Model UT81A/B: OPERATING MANUAL

Ω

Note1. Insert the red test lead into the Ω 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 measured value shows on the display.

When measuring resistance, the corresponding
functional buttons:
RES REL Rang Rang
F1 F2 F3 F4

F1: toggle to diode mode
F2: relative mode
F3: select to a range up
F4: select to a range down

When measuring low resistance, the test leads can
add 0.1Ω to 0.2Ω of error to resistance measurement.
To test the leads, touch the probe tips together and
read the resistance of the leads. Take the reading
obtained to subtract the resistance of the leads to
get the final reading.
For high-resistance measurement (>1MΩ) or low
resistance measurement (<40Ω), it is normal taking
several seconds to obtain a stable reading.
The LCD displays “OL” indicating open-circuit without
input.
When resistance measurement has been completed,
disconnect the connection between the testing leads
and the circuit under test and remove testing leads
away from the input terminals.

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Model UT81A/B: OPERATING MANUAL

Figure 3-7. Diode Test

To avoid harms to you, please do not attempt to
input voltages higher than 60V DC or 42V rms AC.

To avoid damages to the Meter or to the devices
under test, disconnect circuit power and discharge
all the high-voltage capacitors before testing diodes.

Warning

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

To test the diode out of a circuit, set up the Meter as
Figure 3-7 and proceed as follows:

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Model UT81A/B: OPERATING MANUAL

Ω

Note1. Insert the red test lead into the Ω 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 red test lead
polarity is “+” while the black test lead polarity is “—
“.
The measured value shows on the display.

When measuring diode, the corresponding functional
buttons:
DIODE REL

F1 F2
F1: toggle to continuity buzzer
F2: relative mode

Connect the test leads to the proper terminals as
said above to avoid error display.
The LCD will display OL indicating either open
circuit or wrong polarity connection.
The unit of diode is volt (V), displaying the positive­connection voltage-drop value.
When diode testing has been completed, disconnect
the connection between the testing leads and the
circuit under test and remove the test leads away
from the input terminals.

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Model UT81A/B: OPERATING MANUAL

Figure 3-8. Continuity Test

To avoid harms to you, please do not attempt to
input voltage higher than 60V DC or 42V rms AC.

To avoid possible damages to the Meter or to the
devices under test, disconnect circuit power and
discharge all the high-voltage capacitors before
measuring continuity.

Warning

To test for continuity, set up the Meter as Figure 3-8
and do the following:

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Model UT81A/B: OPERATING MANUAL

Ω

Note1. Insert the red test lead into the W 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
tested.

4. The tested circuit overload resistance value shows
on the display.

5. The beeper comes on continuously for open
conditions, that is test resistance 10W.

6. The beeper does not sound when the test resistance
is 100W

When measuring continuity buzzer, the corresponding
functional buttons:
CONTINUITY REL

F1 F2

F1: toggle to resistance measurement mode
F2: relative mode

When continuity testing has been completed,
disconnect the connection between the testing leads
and the circuit under test and remove the test leads
away from the input terminals.

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Model UT81A/B: OPERATING MANUAL

Figure 3-9. Measuring Frequency / Duty Cycle

To avoid harms to you, please do not attempt to
input voltage higher than 42V rms.

Warning

To measure frequency and duty cycle, connect the
Meter as Figure 3-9 and do the following:

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

2. Set the rotary switch to Hz.

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

4. The measured value shows on the display.

5. Press MODE button to toggle between Multimeter
mode and Scope mode.

6. Press F1 to toggle between frequency and duty cycle
measurement.

When measuring frequency and duty cycle, the
corresponding functional buttons:

Freq/Duty

F1

F1: toggle between frequency and duty cycle

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Model UT81A/B: OPERATING MANUAL

Note

The requirement of Input amplitude “a” is as follows:

When 1MHz: 300 mV a 30Vrms;

1MHz: 600 mV a 5Vrms
It is normal to have few seconds run time when
switch from other functions to these functions.
When Hz or duty cycle measurement has been
completed, disconnect the connection between the
testing leads and the circuit under test and remove
the test leads away from the input terminals.

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Model UT81A/B: OPERATING MANUAL

Figure 3-10. Measuring Capacitance

T o ensure accuracy, the Meter inside is discharged
against the tested capacitor

T o avoid damage to the Meter or to the equipment
under test, disconnect circuit power and discharge
all high-voltage capacitors before measuring
capacitance.

Warning

To measure capacitance, set up the Meter as shown in
Figure 3-10 and proceed as follows:

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Model UT81A/B: OPERATING MANUAL

Capacitors larger than 10 F take longer time.
If the tested capacitor has polarity , connect the red
test lead to positive side and black test lead to
negative side.
When capacitance measurement has been
completed, disconnect the connection between the
testing leads and the circuit under test and remove
the test leads away from the input terminals of the
Meter.

1.

2.

3.

4.

Insert the red test lead into theterminal and the
black test lead into the COM terminal.
Set the rotary switch to measurement mode, the
Meter may display a fixed reading which is a internal
distributed capacitor value. For testing less than
40nF capacitor, the tested value must subtract the
internal distributed capacitor value to maintain the
accuracy.
To improve the accuracy, press F2 REL with the
test leads open to subtract the residual capacitance
of the Meter and the test leads.
It is recommended to use as short as test lead
carrying out measurement to reduce the effect of
internal distributed capacitor.

When measuring capacitance, the corresponding
functional buttons:
Capacity REL

F1 F2

F2: relative mode

Note

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Model UT81A/B: OPERATING MANUAL

Chapter 4

Using Software

When using the Software, please refer to the Installation Guide of the included CD-ROM.

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Model UT81A/B: OPERATING MANUAL

Chapter 5

Maintaining The Test Tool

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

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.

Warning

A. General Service

l
l

l
l

l

Periodically wipe the case with a damp cloth and
mild detergent. Do not use abrasives or solvents.
T o clean the terminals with cotton bar with detergent,
as dirt or moisture in the terminals can affect
readings.
Turn the Meter to OFF when it is not in use.
Take out the battery when it is not using for a long
time.
Do not use or store the Meter in a place of humidity ,

high temperature, explosive, inflammable and strong
magnetic field.

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Model UT81A/B: OPERATING MANUAL

1.Remove the
battery compartment

2.Remove the
case bottom

3.Install fuses with
correct type and
specification

Figure 5-1. Fuse Replacement

B. Replacing the Fuses

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

Warning

Follow Figure 5-1 and proceed as follows to replace
the Meter’s fuse:

Turn the rotary switch to OFF and remove all
connections from the terminals.
Remove the screw from the battery compartment,
and separate the battery compartment from the case
bottom.
Remove the three screws from the case bottom,
and separate the case bottom from the case top.
Remove the fuse by gently prying one end loose,
then take out the fuse from its bracket.
Install ONLY replacement fuses with the identical
type and specification as follows and make sure the
fuse is fixed firmly in the bracket.
Fuse 1: F0.5AH/250V, ø5 x 20mm
Fuse 2: F10AH/250V, ø5 x 20mm
Rejoin the case bottom and case top, battery
compartment and case bottom, and install the 5
screws.

l
l

l
l
l

l

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

40

Model UT81A/B: OPERATING MANUAL

Figure 5-2. Battery Replacement

C. Replacing the Battery

Warning

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

Make sure the test leads are disconnected from the
circuit being tested before opening the case bottom.

Follow Figure 5-2 and proceed as follows to replace
the battery:

Turn the rotary switch to OFF and remove all
connections from the terminals.
Remove the screw from the battery compartment,
and separate the battery compartment from the case
bottom.
Replace with 4 pieces new 1.5V (R6P) batteries.
Rejoin the case bottom and battery compartment,
and reinstall the screw.

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Model UT81A/B: OPERATING MANUAL

Chapter 6

Specifications

Safety and Compliances

Refer to different range input protection voltage

IEC 61010 CAT. II 1000V, CAT.III 600V overvoltage
and double insulation standard
F0.5AH/250V, ø5×20mm
F10AH/250V, ø5×20mm

Maximum Voltage between any Terminal and
Grounding
Certification
Compliances

Fused Protection for mA input terminal:
Fused Protection for 10A input terminal:

42

Model UT81A/B: OPERATING MANUAL

Physical Specifications

Digital: 3999 counts on display ; updates 2-3 times / second.
0oC~40oC (32oF~104oF)

-10oC~50oC (14oF~122oF)
75% @ 0oC~40oC;
0% @ -10oC~50oC.

Operating: 2000m;
Storage: 10000m.

1.5V (R6) x 4 Batteries or Power adaptor. Check carefully about the

working voltage of power adaptor before use.
l In a radio field of 1 V/m below:
Overall Accuracy = Specified Accuracy + 5% of Range
l In a radio field of 1 V/m above:
No assigned accuracy is specified.
200 x 100 x 48mm.
Approx. 498g (including battery)

Display (LCD)
Operating Temperature
Storage Temperature
Relative Humidity

Altitude

Battery Type

Electromagnetic Compatibility

Dimensions (H x W x L)
Weight

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Model UT81A/B: OPERATING MANUAL

General Specifications ( Digital Multimeter)

When it is under Multimeter mode, you could select either auto or
manual ranging.
Auto, negative polarity displays “-“
Display OL
Display

Range

Polarity
Overloading
Battery Deficiency

General Specifications (Scope)

160 x 160 Monochrome
Auto set the Meter according to the tested signal size
Display OL
10 screens and setups
Optically isolated to ensure safety
Allowing viewing at a convenient position and angle.

Display
Auto setting
Overloading
Memory
USB
Tilt Stand

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Model UT81A/B: OPERATING MANUAL

Feature Summary

160 x 160 Monochrome
When it is under multimeter mode, the Meter automatically selects
best range
Beeper sounds for resistance readings below threshold.
Measure signal on or off time in %.
Battery replaceable.

Display
Autorange

Continuity
Duty Cycle
Battery Access Door

Basic Specifications (Digital Multimeter)

Ranges / Description

0 to 1000V
0 to 750V
DC Voltage: 0.8%
AC Voltage: 1%
0 to 10A
0 to 10A
0 to 40MΩ
0 to 100µF
0~10MHz

Function

DC Voltage
AC Voltage
Basic Accuracy

DC Current
AC Current
Resistance
Capacitance
Frequency

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Model UT81A/B: OPERATING MANUAL

Basic Specifications (Scope)

Sampling rate
Sampling rate / Scale
Updating rate
Trigger types

Timebase Range

Timebase accuracy

40M per second
20 pixels
>5
Free Run / Normal /
Single Shot
100ns/div~5 sec /div
(1-2-5)

(0.1% + 1pix)

Bandwidth
Channel
Coupling
Voltage resolution

Input Impedance

Accuracy
Maximum input voltage
Voltage Sensitivity

UT81A:2MHz,UT81B:8MHz
Single
DC
8 Bits

10MΩ (excluding Multimeter part)

(5%+1pix)
1000Vp-p
20mV/div~500V/div (1-2-5)

Horizontal Vertical

Detailed Accuracy Specifications

Accuracy: ([% of reading] + [number of least significant digits]), guarantee for 1 year.
Operating temperature: 18oC~28oC
Relative humidity: <75%RH

46

Model UT81A/B: OPERATING MANUAL

A. DC Voltage

400mV
4V
40V
400V
1000V

Range Resolution Accuracy Overload Protection Input Impedance

100µV
1mV
10mV
100mV
1V

(0.8%+8)

(0.1%+8)

1000V DC or AC

Around 10MΩ
(excluding waveform)

B. AC Voltage

4V
40V
400V
750V

Range Resolution Accuracy Overload Protection Input Impedance

1mV
10mV
100mV
1V

(1%+15)

(1.2%+15)

1000V DC or AC

Around 10MΩ
(excluding waveform)

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Model UT81A/B: OPERATING MANUAL

C. DC Current

F0.5AH/250V, ø5×20mm

F10AH/250V, ø5×20mm.
(Continuous

measurement 10 seconds

and interval more than 15 minutes.)

Range Resolution Accuracy Overload Protection

400µA
4000µA
40mA
400mA
4A
10A

0.1µA
1µA
10µA
100µA
1mA
10mA

(1%+8)

(1.2%+8)

(1.5%+8)

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Model UT81A/B: OPERATING MANUAL

D. AC Current

F0.5AH/250V, ø5×20mm

F10AH/250V, ø5×20mm
(Continuous measurement 10 seconds
and interval more than 15 minutes.)

Range Resolution Accuracy Overload Protection

400µA
4000µA
40mA
400mA
4A
10A

0.1µA
1µA
10µA
100µA
1mA
10mA

(1.5%+8)

(2%+8)

(2.5%+5)

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Model UT81A/B: OPERATING MANUAL

400Ω
4kΩ
40kΩ
400kΩ
4MΩ
40MΩ

250VDC or AC rms

Range Resolution Accuracy Overload Protection

E. Resistance

0.1Ω
1Ω
10Ω
100Ω
1kΩ
10kΩ

(1.2%+5)

(1%+5)

(1.2%+5)
(1.5%+5)

Range Resolution Overload Protection Remarks

F. Diode Test

A good silicon junction drops
between

0.5V and 0.8V.

250V DC or AC1mV

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Model UT81A/B: OPERATING MANUAL

Range Resolution Overload Protection Remarks

G. Continuity Test Test

 The buzzer sounds when the test resistance
is 10Ω.
 The buzzer does not sound when the
test resistance is 100Ω.

250V DC or AC

0.1Ω

10Hz~10MHz

0.1%~99.9%

250V DC or AC rms

Range Resolution Accuracy Overload Protection

0.001Hz

0.1%

(0.1%+3)

Reading

for reference only

H. Frequency and Duty Cycle %

51

Model UT81A/B: OPERATING MANUAL

40nF
400nF
4µF
40µF
100µF

250V DC or AC rms

Range Resolution Accuracy Overload Protection

10pF
100pF
1nF
10nF
100nF

Under REL mode: (3%+10)

(3%+8)

(4%+8)

I. Capacitance