Unit UT20B User manual

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Title
Overview
Unpacking Inspection
Safety Information
Rules For Safe Operation
International Electrical Symbols
Rotary Switch
Display Symbols
Measurement Operation
A. AC Voltage Measurement
B. DC Current Measurement
C. Square Wave Output
D. Battery Test
E. Diodes Test
F. Measuring Resistance
G. DC Voltage Measurement
Table of Contents (1)
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Table of Contents (2)
Title
General Specifications
Accuracy Specifications
A. AC Voltage
B. DC Current
C. Square Wave Output
D. Battery Test
E. Diodes Test
F. Resistance Test
G. DC Voltage
Maintenance
A. General Service
B. Replacing the Battery
C. Replacing the Fuses
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Model UT20B: OPERATING MANUAL

This Operation 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.
Digital Multimeter Model UT20B (hereafter referred to as "the Meter") is a pocket-
size hand-held digital multimeter with advanced design, multiple functions, and
reliable performance. Because of its small size, it is very convenience for user to
work with it. It is very easy to operate, so it is suitable to the beginner of multimeter.
Besides the basic functions, the Meter also has some extraordinary functions such
as battery test and square wave output.
Overview
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Model UT20B: OPERATING MANUAL

Open the packing 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.
Item
1
2
3
Description
Operating Manual
Test Lead (affixed onto the Meter)
12V Battery (A23) (installed)
Qty
1 piece
1 pair
1 piece
Unpacking Inspection
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Model UT20B: OPERATING MANUAL

This Meter complies with the standards IEC61010: in pollution degree 2, overvoltage
category (CAT. II 300V) and double insulation.
CAT. II: Local level, appliance, PORTABLE EQUIPMENT etc., with smaller transient
voltage overvoltages than CAT. III.
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 9.
Safety Information
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Model UT20B: 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:
lBefore 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.
lInspect the test leads for damaged insulation or exposed metal. Check
the test leads for continuity.
lDo not apply more than the rated voltage, as marked on the Meter, between
the terminals or between any terminal and grounding.
lThe 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.
Rules For Safe Operation (1)
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Model UT20B: OPERATING MANUAL

Rules For Safe Operation (2)
lWhen 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.
lUse the proper function and range for your measurements.
lDo 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.
lWhen using the test leads, keep your fingers behind the finger guards.
lDisconnect circuit power and discharge all high-voltage capacitors before
testing resistance, diodes or current.
lBefore measuring current, check the Meter's fuses and turn off power to
the circuit before connecting the Meter to the circuit.
lReplace 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.
lTurn the Meter power off before opening the Meter case.
lWhen servicing the Meter, use only the same model number or identical
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Model UT20B: OPERATING MANUAL

Rules For Safe Operation (3)
electrical specifications replacement parts.
lThe internal circuit of the Meter shall not be altered at will to avoid damage
of the Meter and any accident.
lSoft 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.
lThe Meter is suitable for indoor use.
lTurn the Meter off when it is not in use and take out the battery when not
using for a long time.
lConstantly check the battery as it may leak when it has been using for
some time, replace the battery as soon as leaking appears. A leaking
battery will damage the Meter.
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Model UT20B: OPERATING MANUAL

International Electrical Symbols
AC (Alternating Current)
DC (Direct Current)
Grounding.
Double Insulated.
Deficiency of Built-In Battery.
Diode.
Fuse.
Warning. Refer to the Operating Manual.
Conforms to Standards of European Union.
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Model UT20B: OPERATING MANUAL

Below table indicated for information about the rotary switch positions.
Rotary Switch
Rotary Switch Position
OFF
V
A
Ω
V
Function
Turn on or off the power.
AC voltage measurement range from 200V to 300V.
DC current measurement range from 2000µA to 200mA.
Square wave output.
Battery test (1.5V & 9V battery).
Diode test.
Resistance measurement range from 200Ωto 2000kΩ.
DC voltage measurement range from 200mV to 300V.
Display Symbols
Symbol Meaning
Indicates negative reading.
The input value is too large for the selected range.
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Model UT20B: OPERATING MANUAL

Measurement Operation (1)
A. AC Voltage Measurement
Warning
To avoid harms to you or damages to the Meter from electric shock, please
do not attempt to measure voltages higher than 300V rms although readings
may be obtained.
The AC voltage measurement positions are: 200V and 300V. To measure AC Voltage,
connect the Meter as follows:
1. Set the rotary switch to an appropriate measurement positions in Vrange.
2. Connect the test leads across with the object being measured.
The measured value shows on the display, which is effective value of sine wave
(mean value response).
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Model UT20B: OPERATING MANUAL

Measurement Operation (2)
Note
lIf the value of voltage to be measured is unknown, use the maximum
measurement position (300V) and reduce the range step by step until a
satisfactory reading is obtained.
lIn each range, the Meter has an input impedance of approx. 0.5MΩ. This loading
effect can cause measurement errors in high impedance circuits. If the circuit
impedance is less than or equal to 1kΩ, the error is negligible (0.2% or less).
lWhen AC voltage measurement has been completed, disconnect the connection
between the testing leads and the circuit under test.
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Model UT20B: OPERATING MANUAL

Measurement Operation (3)
B. DC Current Measurement
Warning
Never attempt an in-circuit current measurement where the open-circuit voltage
between the circuit and ground is greater than 300V.
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 current measurement has 3 measurement positions on the rotary switch: 2000µA,
20mA and 200mA.
To measure current, do the following:
1. Turn off power to the circuit. Discharge all high-voltage capacitors.
2. Set the rotary switch to an appropriate measurement position in Arange.
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Model UT20B: OPERATING MANUAL

Measurement Operation (4)
3. 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.
4. Turn on power to the circuit.
The measured value shows on the display.
Note
lIf the value of current to be measured is unknown, use the maximum measurement
position (200mA) and reduce the range step by step until a satisfactory reading
is obtained.
lWhen current measurement has been completed, disconnect the connection
between the testing leads and the circuit under test.
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Model UT20B: OPERATING MANUAL

Measurement Operation (5)
C. Square Wave Output
Warning
To avoid damages to the Meter, do not allow output terminals to reach higher
than 10V.
To measure square wave output proceed as follows:
1. Set the rotary switch to .
2. Connect the test leads across with the object being measured.
The measured value shows on the display.
Note
lThe frequency is approx. 50Hz.
lThe output voltage range will be over 3Vpp when it is loaded 1MΩ.
lWhen square wave output testing has been completed, disconnect the connection
between the testing leads and the circuit under test.
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Model UT20B: OPERATING MANUAL

Measurement Operation (6)
D. Battery Test
To test the battery proceed as follows:
1. Set the rotary switch to the 1.5V or 9V measurement position in range.
2. Connect the test leads across with the battery being measured ensuring the
polarity is correct.
The measured value shows on the display, which is the voltage between the
cathode and anode of the battery.
Note
lWhen battery testing has been completed, disconnect the connection between
the testing leads and the battery under test.
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Model UT20B: OPERATING MANUAL

E. Diodes Test
Warning
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.
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 a diode out of a circuit, connect the Meter as follows:
1. Set the rotary switch to .
Measurement Operation (7)
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Model UT20B: OPERATING MANUAL

2. 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.
Note
lIn 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.
lConnect the test leads to the proper terminals as said above to avoid error
display.
lThe LCD will display " " indicating open-circuit for wrong connection.
lThe unit of diode is Volt (V), displaying the positive-connection voltage-drop
value.
lWhen diode testing has been completed, disconnect the connection between
the testing leads and the circuit under test.
Measurement Operation (8)
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Model UT20B: OPERATING MANUAL

F. Measuring Resistance
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.
The resistance measurement positions are: 200Ω, 2000Ω, 20kΩ, 200kΩand 2000kΩ.
To measure resistance, connect the Meter as follows:
1. Set the rotary switch to an appropriate measurement position in Ωrange.
2. Connect the test leads across with the object being measured.
The measured value shows on the display.
Measurement Operation (9)
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Model UT20B: OPERATING MANUAL

Note
lIf the value of resistance to be measured is unknown, use the maximum
measurement position (2000kΩ) and reduce the range step by step until a
satisfactory reading is obtained.
lThe test leads can add 0.1Ω to 0.2Ωof error to resistance measurement. To
obtain precision readings in low-resistance measurement, that is the range of
200Ω,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.
lFor high-resistance measurement (>1MΩ), it is normal taking several seconds
to obtain a stable reading.
lIf Ωreading with shorted test leads is not 0.5Ω, check for loose test leads, or
incorrect function selection.
Measurement Operation (10)
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Model UT20B: OPERATING MANUAL