Unit UT90A User manual

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 Voltage Measurement
B. AC Voltage Measurement
C. DC Current Measurement
D. AC Current Measurement
E. Resistance Measurement
F. Testing Diodes & Continuity
G. Battery Test
General Specifications
Accuracy Specifications
A. DC Voltage
B. AC Voltage
C. DC Current
D. AC Current
E. Resistance
F. Diodes & Continuity Test
Maintenance
A. General Service
B. Replacing the Fuses
C. Replacing the Battery
3
4
5
6
8
9
10
32
11
12
14
14
16
17
19
20
22
24
26
28
28
28
29
29
30
30
31
31
31
Model UT90A: 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 Voltage Measurement
B. AC Voltage Measurement
C. DC Current Measurement
D. AC Current Measurement
E. Resistance Measurement
F. Testing Diodes & Continuity
G. Battery Test
General Specifications
Accuracy Specifications
A. DC Voltage
B. AC Voltage
C. DC Current
D. AC Current
E. Resistance
F. Diodes & Continuity Test
Maintenance
A. General Service
B. Replacing the Fuses
C. Replacing the Battery
Model UT90A: OPERATING MANUAL
2

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
To avoid electric shock or personal injury, read the
"Safety Information" and "Rules for Safe Operation"
carefully before using the Meter.
The Model UT90A (hereafter referred to as “the Meter”)
is a 1999 counts 3 1/2 digits multimeter with stabilized
functions, safe design, and reliable performance.
In addition to the conventional measuring function, such
as DC/AC voltage, DC/AC current, resistance, diode and
continuity, it is also a highly applied digital electrical tester
of good performance with battery test, large LCD full
icons display, full overload protection and streamline
outlook.
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 Voltage Measurement
B. AC Voltage Measurement
C. DC Current Measurement
D. AC Current Measurement
E. Resistance Measurement
F. Testing Diodes & Continuity
G. Battery Test
General Specifications
Accuracy Specifications
A. DC Voltage
B. AC Voltage
C. DC Current
D. AC Current
E. Resistance
F. Diodes & Continuity Test
Maintenance
A. General Service
B. Replacing the Fuses
C. Replacing the Battery
Model UT90A: OPERATING MANUAL
3

Unpacking Inspection
Open the package case and take out the Meter. Check
the following items carefully to see any missing or
damaged part:
In the event you find any missing or damage, please
contact your dealer immediately.
Holster
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 Voltage Measurement
B. AC Voltage Measurement
C. DC Current Measurement
D. AC Current Measurement
E. Resistance Measurement
F. Testing Diodes & Continuity
G. Battery Test
General Specifications
Accuracy Specifications
A. DC Voltage
B. AC Voltage
C. DC Current
D. AC Current
E. Resistance
F. Diodes & Continuity Test
Maintenance
A. General Service
B. Replacing the Fuses
C. Replacing the Battery
Model UT90A: OPERATING MANUAL
4
Item
1
2
3
4
Description
English Operating Manual
Test Lead
9V Battery (NEDA1604, 6F22 or 006P)
Qty
1 piece
1 pair
1 piece
1 piece

Safety Information
This Meter complies with standards IEC61010: in pollution
degree 2, overvoltage category (CAT. II 1000V, CAT. III
600V) and double insulation.
CAT.II: Local level, appliance, PORTABLE EQUIPMENT
etc., with smaller transient 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.
Model UT90A: OPERATING MANUAL
5

Rules For Safe Operation (1)
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 When using the test leads, keep your fingers
behind the finger guards.
l Do not apply more than the rated voltage, as
marked on the Meter, between the terminals or
between any terminal and grounding.
l When the Meter working at an effective voltage
over 60V in DC or 30V 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 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 Disconnect circuit power and discharge all high-
voltage capacitors before testing current,
resistance, diodes or continuity.
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.
Model UT90A: OPERATING MANUAL
6

Rules For Safe Operation (2)
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 Turn off the Meter 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.
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.
l The Meter is suitable for indoor use.
Model UT90A: OPERATING MANUAL
7

International Electrical Symbols
AC (Alternating Current).
DC (Direct Current).
AC or DC.
Grounding.
Double Insulated.
Deficiency of Built-In Battery.
Continuity Test.
Diode.
Fuse.
Warning. Refer to the Operating Manual.
Conforms to Standards of European Union.
Model UT90A: OPERATING MANUAL
8

The Meter Structure (see figure 1)
9
( figure 1)
1 LCD Display.
2 Hold Button.
3 Rotary Switch.
4 Input Terminals.
5 Power Button.
Model UT90A: OPERATING MANUAL

10
AC Current Measurement Range from
0.1µA to 10A
Model UT90A: OPERATING MANUAL
µ

11
Functional Buttons
Below table indicated for information about the functional
button operations.
AC voltage measurement.
Turn the power on and off.
l Press HOLD once to enter hold mode.
l Press HOLD again to exit hold mode
and the present value is shown.
l In Hold mode, is displayed
HOLD
Model UT90A: OPERATING MANUAL

12
Display Symbols(1) (see figure 2)
( figure 2)
No. Symbol Meaning
1The 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.
2
4Indicates negative reading.
5Test of diode.
6The continuity buzzer is on.
7Date hold is active.
8
High voltage indicator
Indicator for AC voltage or current.
The displayed value is the mean
value.
3AC
Connect
Terminal
Indicator of connecting test leads
into different input terminals.
AC
µAmAA
Ω
mVV k M
Ω Ω
Model UT90A: OPERATING MANUAL

Display Symbols(2) (see figure 2)
Ω: Ohm. The unit of resistance.
kΩ: kilohm.1 x 103or 1000 ohms.
MΩ: Megaohm. 1 x 106or
1,000,000 ohms.
µA, mA, A
A: Amperes (amps). The unit of
current.
mA: Milliamp. 1 x 10-3 or 0.001
amperes.
µA: Microamp. 1x 10-6 or 0.000001
amperes.
V: Volts. The unit of voltage.
mV: Millivolt. 1 x 10-3 or 0.001 volts.
No. Symbol Meaning
9
Ω,kΩ,MΩ
mV, V
13
Model UT90A: OPERATING MANUAL

14
Measurement Operation(1)
A.DC Voltage Measurement (see figure 3)
red black
( 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 DC/750V AC although
readings may be obtained.
The DC voltage ranges are: 200.0mV, 2.000V, 20.00V,
200.0V and 1000V.
To measure DC voltage, connect the Meter as follows:
1. Insert the red test lead into the VΩterminal and
the black test lead into the COM terminal.
2. Set the rotary switch to an appropriate measurement
position in V .
3. Connect the test leads across with the object being
measured.
The measured value shows on the display.
Note
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.
Model UT90A: OPERATING MANUAL

15
Measurement Operation(2)
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. 10MΩ. This loading effect can cause
measurement errors in high impedance circuits. If
the circuit impedance is less than or equal to 10kΩ,
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.
Model UT90A: OPERATING MANUAL

16
Measurement Operation(3)
B.AC Voltage Measurement (see figure 3)
red black
( 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 DC/750V AC although
readings may be obtained.
The AC voltage ranges are: 2.000V, 20.00V, 200.0V and
750.0V.
To measure AC Voltage, connect the Meter as follows:
1. Insert the red test lead into the VΩterminal 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).
Note
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.
Model UT90A: OPERATING MANUAL

17
Measurement Operation(4)
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. 10MΩ. This loading effect can cause
measurement errors in high impedance circuits. If the
circuit impedance is less than or equal to 10kΩ, 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.
C.DC Current Measurement (see figure 4)
Warning
Never attempt an in-circuit current measurement
where the open circuit voltage between terminals
and ground is greater than 60V DC or 30V rms.
If the fuse burns out during measurement, the Meter
may be damaged or the operator himself may be hurt.
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.
black red
( figure 4)
Model UT90A: OPERATING MANUAL

18
The measurement ranges of DC current are: 200.0µA,
2.000mA, 20.00mA, 200.0mA and 10.00A.
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 µAmA or 10A
terminal and the black test lead into the COM terminal.
3. Set the rotary switch to an appropriate measurement
position in Arange.
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.
Measurement Operation(5)
Note
l If the value of current to be measured is unknown,
use the maximum measurement position (10A) and
10A terminal, and reduce the range step by step until
a satisfactory reading is obtained.
l When DC current measurement has been completed,
disconnect the connection between the testing leads
and the circuit under test.
Model UT90A: OPERATING MANUAL

19
D. AC Current Measurement (see figure 4)
Warning
Never attempt an in-circuit current measurement
where the voltage between terminals and ground is
greater than 60V.
If the fuse burns out during measurement, the Meter
may be damaged or the operator himself may be hurt.
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.
The measurement ranges of AC current are: 200.0µA,
2.000mA, 20.00mA, 200.0mA and 10.00A.
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 µAmA or 10A
terminal and the black test lead into the COM terminal.
3. Set the rotary switch to an appropriate measurement
position in A range.
Measurement Operation(6)
black red
( figure 4)
Model UT90A: OPERATING MANUAL

20
Measurement Operation(7)
E. Measuring Resistance (see figure 5)
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.
red black
( figure 5)
Model UT90A: OPERATING MANUAL