UNI-T UT58A, UT58B, UT58C Operating Manual

1

Table of Contents

Title Page

Overview
Unpacking Inspection
Safety Information
Rules For Safe Operation
International Electrical Symbols
The Meter Structure
Rotary Switch
Functional Buttons
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
(UT58B/UT58C only)
H. Measuring Transistor
I. Frequency Measurement (UT58C only)
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 (UT58B/UT58C only)
J. Transistor Test

3

10

4

11

12
14

14
15

17
18

20
21

22
23
24
24
25
26

27
27
27

28
28
29
29

29
30

30
31

5
6
8
9

Model UT58A/B/C: OPERATING MANUAL

Title Page

K. Frequency (UT58C only)
Maintenance
A. General Services
B. Replacing the Fuses
C. Replacing the Battery

31
32
32

32
33

Model UT58A/B/C: OPERATING MANUAL

2

Overview

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

Digital Multimeters Model UT58A, UT58B and UT58C
(hereafter referred to as “the Meter”) are 3 1/2 digits with
ex-large LCD, steady operations, fashionable structure
and highly reliable hand-held measuring instrument. The
Meter uses large scale of integrated circuit and has full
range overload protection. The Meter not only can
measure AC/DC Voltage, AC/DC Current, Resistance,
Capacitance, Temperature, Frequency, T ransistor, Diode
and Continuity , but also have Data Hold, Full Icon Display,
Overload Protection and Sleep Mode features.

Model UT58A/B/C: OPERATING MANUAL

3

Unpacking Inspection

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

1 English Operating Manual
2 Test Lead
3 Multi-Purpose Socket
4 Point Contact Temperature Probe
(UT58B/UT58C only)
5 9V Battery (NEDA 1604, 6F22 or 009P)

4

Model UT58A/B/C: OPERATING MANUAL

Item

Description

Qty

1 piece
1 pair
1 piece
1 piece

1 piece

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.

5

Model UT58A/B/C: OPERATING MANUAL

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 grounding.
l 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.
l 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.
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.

Rules For Safe Operation (1)

6

Model UT58A/B/C: OPERATING MANUAL

Rules For 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 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.

7

Model UT58A/B/C: 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.

Model UT58A/B/C: OPERATING MANUAL

8

(figure 1)

The Meter Structure (see figure 1)

1. LCD Display.

2. HOLD Button.

3. Rotary Switch.

4. Input Terminals.

5. POWER

Model UT58A/B/C: OPERATING MANUAL

9

Functional Buttons

Below table indicated for information about the functional
button operations.

POWER
(Yellow
Button)

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.

Button Operation Performed

Model UT58A/B/C: OPERATING MANUAL

11

No. Symbol Meaning

The battery is low.

Warning: To avoid false
readings, replace the battery as
soon as the battery indicator
appears.

4

Indicates negative reading.

5

Test of diode.

6

The continuity buzzer is on.

7

Date hold is active.

8

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

3

AC

Connect
Terminal

Indicator of connecting test leads
into different input terminals.

(figure 2)

2

1

Model UT58A/B/C: OPERATING MANUAL

12

Connect Test Leads

COM

Ω

FmVV k M

Ω Ω

µ

nF FkHz AmAA

µ

A

Ω

V

µ

AmA

µA, mA, A

No. Symbol Meaning

9

Ω,kΩ,MΩ

mV, V

µF nF

o

C

Model UT58A/B/C: OPERATING MANUAL

13

black red

(figure 3)

Warning
To avoid harms to you or damages 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 750V

Measurement Operation(1)

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

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

1. Insert the red test lead into the HzVΩ (UT58C) or
VΩ (UT58A/UT58B) 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.

Model UT58A/B/C: OPERATING MANUAL

14

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 himself may be hurt.

Measurement Operation(2)

Model UT58A/B/C: OPERATING MANUAL

15

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

Measurement Operation(3)

The DC Current ranges are:
Model UT58A/ UT58B: 20µA,2mA,20mA, 200mA and 20A.
Model UT58C: 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 µAmA ( UT58A)
or mA (UT58B/UT58C) 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.

Model UT58A/B/C: OPERATING MANUAL

16

Measurement Operation(4)

Warning
To avoid damages 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 5)

The resistance ranges are:
Model UT 58A/UT58B:200Ω, 2kΩ, 20kΩ, 2MΩ,20MΩ and
200MΩ.
Model UT 58C:200Ω, 2kΩ, 20kΩ, 2MΩ and 20MΩ.

1. Insert the red test lead into the Hz VΩ (UT58C) or
VΩ (UT58A/UT58B) 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.

Model UT58A/B/C: OPERATING MANUAL

17

black red

(figure 6)

Note

l The test leads can add 0.1to 0.2Ω of error to the slow-
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 is normal taking 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.

Model UT58A/B/C: OPERATING MANUAL

18

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 harms to you, 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 (UT58C) or
VΩ (UT58A/UT58B) 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.

Model UT58A/B/C: OPERATING MANUAL

19

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 harms to you, please do not attempt to input
voltages higher than 60V DC or 30V 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 for continuity.

To test for continuity, connect the Meter as below:

1. Insert the red test lead into Hz VΩ (UT58C) or
VΩ (UT58A/UT58B) 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 >70

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.

Model UT58A/B/C: OPERATING MANUAL

20

21

(figure 9)

9

Model UT58A/B/C: OPERATING MANUAL

22

Model UT58A/B/C: OPERATING MANUAL

23

POWER

Model UT58A/B/C: OPERATING MANUAL

24

Model UT58A/B/C: OPERATING MANUAL

25

General Specifications

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

l

Fused Protection for
l AmA Input Terminal : CE Version: 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 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 : 179x88x39mm.
l Weight : Approx.380g (including

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

Model UT58A/B/C: OPERATING MANUAL

26

l Relative Humidity : 75%@00C~300C;
50%@300C~400C

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
750V

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
The

500Hz reading is for reference
l Displays effective value of sine wave (mean value
response).

Accuracy Specifications(1)

Accuracy:

(a% reading + b digits),guarantee for 1 year.
Operating temperature:18oC~28oC.
Relative humidity: 75%RH.

Model UT58A/B/C: OPERATING MANUAL

27

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~400Hz
l At 20A Range:

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

20µA

2mA

20mA

200mA

20A

0.01µA
1µA

10µA

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

Fuse 0.5A, 250V,

fast type,

5x20mm

Model

UT58A

UT58ABC

UT58AB
UT58ABC
UT58ABC

Model UT58A/B/C: OPERATING MANUAL

28

UT58ABC

UT58ABC
UT58ABC
UT58ABC
UT58ABC

UT58AB

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

Range Resolution

Accuracy

(4.0%+3)

Range Resolution

Accuracy

7

Model UT58A/B/C: OPERATING MANUAL

30

Accuracy Specifications(5)

J. Transistor test

Range Resolution

Accuracy±(a% reading + b digits)

hFE 1β Vce 3V Ibo 10µA 1000βMAX

K. Frequency ( UT58C only)

Range Resolution

Overload
Protection

Accuracy

2kHz 1Hz
20kHz 10Hz

±(1.5%+5) 250V AC

Model UT58A/B/C: OPERATING MANUAL

31

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

( figure 10)

Model UT58A/B/C: OPERATING MANUAL

32

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.

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

Model UT58A/B/C: OPERATING MANUAL

33

** END **

This operating manual is subject to change without notice.

Model UT58A/B/C: OPERATING MANUAL

34

Model UT58A/B/C: OPERATING MANUAL

35

Copyright 2001 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 UT58A/B/C: OPERATING MANUAL

36