Unit UT90A User manual

Overview
This Operating Manual covers safety information related
to the multimeter. 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"carefully before using the
Meter.
Unpacking Inspection
Open the package case and take out the Meter. Check
the following items carefully for any missing or
damaged part:
In the event you find any missing or damaged item,
please contact your dealer immediately.
Holster
Item
1
2
3
4
Description
English Operating Manual
Test Leads
9V Battery (NEDA 1604, 6F22 or 006P)
Qty
1 pc
1 pair
1 pc
1 pc
Safety Information
This Meter complies with IEC61010 Overvoltage Category
(CAT.II1000V, CAT.III 600V), Double Insulation, Pollution
Degree 2 standards.
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.
ANote identifies the information that user should pay
attention to.
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:
zBefore 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.
zInspect 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.
zWhen using the test leads, keep your fingers
behind the finger guards.
zDo not apply more than the rated voltage, as
marked on the Meter, between the terminals or
between any terminal and grounding.
zWhen 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.
zUse the proper terminals, function, and range
for your measurements.
zThe rotary switch should be placed in the right
position and no any changeover of range shall
be made during measurement to prevent damage
of the Meter.
zDisconnect circuit power and discharge all high-
voltage capacitors before testing current,
resistance, diodes or continuity.
zReplace 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.
zWhen servicing the Meter, use only the replacem
-ent parts with the same model number or identical
electrical specifications.
zThe internal circuit of the Meter shall not be
altered at will to avoid damage of the Meter and
any accident.
zSoft 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.
zTurn off the Meter when it is not in use and
take out the battery when not used for a long
time.
zConstantly 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.
zDo 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.
zThe Meter is suitable for indoor use.
International Electrical Symbols
AC (Alternating Current).
DC (Direct Current).
AC or DC.
Grounding.
Double Insulated.
Low Battery Indication.
Continuity Test.
Diode.
Fuse.
Warning. Refer to the Operating Manual.
Conforms to Standards of European Union.
The Meter Structure (See Figure 1)
Figure 1
1 LCD Display.
2 Hold Button.
3 Rotary Switch.
4 Input Terminals.
5 Power Button.
AC current measurement range from
0.1μA to 10A
μ
Functional Buttons
The table below offers information about the functional
button operations.
AC voltage measurement.
Turn the power on and off.
zPress HOLD once to enter hold mode.
zPress HOLD again to exit hold mode
and the present value is shown.
zIn Hold mode, is displayed
HOLD
Display Symbols (See Figure 2)
Figure2
No. Symbol Meaning
1
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.
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
ΩΩ
4
6
8
9
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.
9
Ω,kΩ,MΩ
mV, V
Measurement Operation
A.Measuring DC Voltage (See Figure 3)
Figure 3
Warning
To avoid harm to you or damage to the Meter from
electric shock, please do not attempt to measure
voltages higher than 1000V 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
zIf 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.
red black
zThe 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.
zIn 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).
zWhen DC voltage measurement has been completed,
disconnect the connection between the testing leads
and the circuit under test.
B.Measuring AC Voltage (See Figure 3)
Warning
To avoid harm to you or damage to the Meter from
electric shock, please do not attempt to measure
voltages higher than 1000V 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 Vrange.
3. Connect the test leads across with the object being
measured.
The measured value shows on the display, which is
RMS value of sine wave (mean value response).
Note
zIf 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.
zThe 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.
zIn 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).
zWhen AC voltage measurement has been completed,
disconnect the connection between the testing leads
and the circuit under test.
C.Measuring DC Current (See 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.
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.
Figure 4
black red
The DC current ranges 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.
Note
zIf 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.
zWhen DC current measurement has been completed,
disconnect the connection between the testing leads
and the circuit under test.
D. Measuring AC Current (See Figure 4)
Warning
Never attempt an in-circuit current measurement
where the 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.
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 AC current ranges 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.
Model UT90A is a 2000-count digital multimeter(referred
to as "the Meter") featuring versatile functions, safe, stable
and reliable performance. It can measure DC/AC voltage,
DC/AC current, resistance, diode and continuity and offer
a battery test. It is also equipped with large LCD, full icon
display, input connection indication, overload protection, etc.
The table below offers
current measurement range
RMS

P/N :110401104423X
E. Measuring Resistance (See Figure 5)
Warning
To avoid damage to the Meter or to the devices
under test, disconnect circuit power and discharge
all the high-voltage capacitors before measuring
resistance.
red black
Figure 5
The resistance ranges are: 200.0 , 2.000k , 20.00k ,
200.0k , 2.000M and 20.00M .
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.
Note
zThe test leads can add 0.1 to 0.2 of error to the
resistance measurement. To obtain precision readings
in low-resistance, that is the range of 200 , 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) = precision
readings of resistance.
zWhenVKRUWHGUHVLVWDQFHYDOXHLVȍ，please
check for loose test leads or other reasons.
zFor high resistance (>1M ), it normally takes
several seconds to obtain a stable reading, and it is
better to choose shorter test lead.
zWhen there is no input, for example in open circuit
condition, the Meter displays “1”.
zWhen resistance measurement has been completed,
disconnect the connection between the testing leads
and the circuit under test.
F.Testing Diodes & Continuity
Warning
To avoid possible damage to the Meter and to the
device under test, disconnect circuit power and
discharge all high-voltage capacitors before testing
diodes and continuity.
Testing Diodes (See Figure 6)
Use the diode test to check diodes, transistors, and other
semiconductor devices. The diode test sends a current
through the semiconductor junction, then measures the
voltage drop across the junction. A good silicon junction
drops between 0.5V and 0.8V.
To test a diode out of a circuit, 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 .
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.
Figure 6
red black
Note
zIn 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.
zConnect the test leads to the proper terminals as
said above to avoid error display.
zThe open-circuit voltage is around 3V when testing
diode.
zThe LCD will display 1indicating open-circuit or
wrong connection.
zThe unit of diode is Volt (V), displaying the positive-
connection voltage-drop value.
zWhen diode testing has been completed, disconnect
the connection between the testing leads and the
circuit under test.
Testing Continuity (See Figure 7)
Figure 7
red black
To test for continuity, connect the Meter as below:
1. Insert the red test lead into the VΩterminal 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 does not sound when the resistance
value is >100Ω. The circuit is disconnected.
The buzzer sounds continuously when the resistance
value is 10Ω. The circuit is in good condition.
Note
zThe LCD displays 1 indicating the circuit being tested
is open.
zOpen-circuit voltage is approx. 3V.
zWhen continuity testing has been completed,
disconnect the connection between the testing leads
and the circuit under test.
G.Battery Test (See Figure 8)
Figure 8
black red
Warning
To avoid damage to the built-In fuse and the Meter,
measure the specified battery type and power supply
only.
To carry out battery test, connect the Meter as follows:
1. Insert the red test lead into the μAmA .
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 red test lead on the anode of the battery
being tested and the black test lead to the cathode
in parallel..
4. The measured value shows on the display.
Note
zThe range of 1.5V only fits for the measurement of 1.5V
Battery. Inside load resistance is 38Ω.
zThe range of 9V only fits for the measurement of 9V
Battery. Inside load resistance is 450Ω.
: H1A, 250V, fast type, 6x25mm
: H10A, 250V, fast type, 6x25mm
General Specifications
zMaximum Voltage between any terminals and
grounding: Refer to different range input protection
voltage.
zFuse Protection
of μA mA terminal
zFuse Protection
of 10A terminal
zMeasurement Speed : Updates 2-3 times /second.
zMaximum Display : 1999.
zTemperature : Operating: 0 oC~40oC(32oF
~104oF).
Storage: -10oC~50oC(14oF
~122oF).
zRelative Humidity : 75% @ 0oCto below 30oC;
50% @ 30oCto 40oC.
zAltitude : Operating : 2000m.
Storage: 10000m.
zBattery Type : One piece of 9V (NEDA
1604 or 6F22 or 006P).
zElectro-Magnetic : When in an RF field of 1V/m:
total accuracy = assigned
accuracy + 5% of the range.
Performance above 1V/m
is not specified.
zLow Battery Indication : Display .
zNegative reading : Display .
zOver Range Indicalion :Displayed Value>1999,display
"1".(The safety and accuracy will
only be guaranteed within the
specified range.)
Equipped with full icons display.
Manual ranging.
Polarity: Automatically display.
Dimensions (HxWxL) : 179 x 88 x 39mm.
Weight : 380g. (including holster
and battery)
z
z
z
z
z
z
Safety/Compliances : ETL CE(IEC/EN61010:
CAT. II 1000V, CAT.III 600V
Pollution,degreez.
zCertification :
Accuracy Specification
Accuracy: (a% reading + b digits),guarantee for 1 year.
Operating temperature:18oC~28oC.
Relative humidity:<75%RH.
Temperature coefficient: 0.1 x (specified accuracy) / 1oC.
Remark: Input impedance: 10MΩ
A. DC Voltage
200mV
2V
20V
200V
1000V
0.1mV
1mV
10mV
100mV
1V
Range Resolution
(0.5%+2)
Overload
Protection
Accuracy
230VAC
(0.8%+3)
1000V DC
or 750V AC
rms.
continuous.
B. AC Voltage
2V
20V
200V
750V
1mV
10mV
100mV
1V
Range Resolution
(0.8%+5)
Overload
Protection
Accuracy
(1.0%+5)
1000V DC
or 750V AC
rms.
continuous.
Remarks:
zInput impedance:10MΩ .
zFrequency response: 40Hz~400Hz.
zDisplay RMS value of sine wave (mean value
response).
Remarks:
zAt 10A Range:
For continuous measurement 10 seconds and
interval time between 2 measurement greater than
15 minutes.
Remarks:
zFrequency response: 40Hz – 400Hz.
zAt 10A Range:
For continuous measurement 10 seconds and
interval time between 2 measurement greater than
15 minutes.
zDisplays RMS value of sine wave (mean value
response).
C. DC Current
200μA
2mA
20mA
200mA
10A
0.1μA
1μA
10μA
0.1mA
10mA
Range Resolution
(0.8%+2)
Overload
Protection
Accuracy
(1.2%+5)
Fuse H1A,250V,
fast type,6x25mm
Fuse H10A,250V,
fast type,6x25mm
D. AC Current
200μA
2mA
20mA
200mA
10A
0.1μA
1μA
10μA
0.1mA
10mA
Range Resolution
(1.0%+5)
Overload
Protection
Accuracy
(2.0%+5)
Fuse H1A,250V,
fast type,6x25mm
Fuse H10A,250V,
fast type,6x25mm
E. Resistance
Range Resolution Overload
Protection
Accuracy
200Ω
2kΩ
20kΩ
200kΩ
2MΩ
20MΩ
0.1Ω
1Ω
10Ω
100Ω
1kΩ
10kΩ
(0.8%+3) +
shorted value
(0.8%+3)
(1.2%+5)
230V rms
F. Diodes & Continuity Test
1mV
1Ω
Range Resolution Overload Protection
230V rms
Remarks:
zAt Range:
Open circuit voltage approximate 3V.
zAt Range:
Open circuit voltage approximate 3V.
The buzzer does not sound when the resistance
value is >100Ω. The circuit is disconnected.
The buzzer sounds continuously when the resistance
value is 10Ω. The circuit is in good condition.
Maintenance
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
zPeriodically wipe the case with a damp cloth and
mild detergent. Do not use abrasives or solvents.
zTo clean the terminals with cotton bar with detergent,
as dirt or moisture in the terminals can affect readings.
zTurn the Meter off when it is not in use and take out
the battery when not used for a long time.
zDo not store the Meter in a place of humidity, high
temperature, explosive, inflammable and strong
magnetic field.
B.Replacing the Fuses (See Figure 9)
Screw
Holster
Figure 9
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.
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 ONLY replacement fuses with the identical
type and specification as follows and make sure the
fuse is fixed firmly in the bracket.
Fuse 1:H10A, 250V, fast type, 6x25 mm.
Fuse 2: H1A, 250V, fast type, 6x25 mm.
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.
C.Replacing the Battery (See Figure 9)
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 the Meter’s battery:
1. Turn the Meter power off and remove all connections
from the terminals.
2. Take the Meter out from the holster.
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.
** END **
This operating manual is subject to change without notice.