Capacitance Measurement; Diode Test - UNI-T UT39B Manual

Model: UT39B
Note:
• The test leads can add 0.1W to 0.3W of error to the resistance measurement. To obtain preci-
sion readings in low-resistance measurement, that is the range of 200W, short-circuit the input
terminals beforehand and record the reading obtained. This is the additional resistance from
the test lead, which need to be deducted from the measured value.
• The LCD display indicates "1" for open circuit or if the tested resistor is of higher value than
the maximum range of the meter.
D. Capacitance Measurement
To avoid damage to the meter, disconnect circuit power and discharge all high voltage capaci-
discharged.
To measure capacity, connect the meter as below:
1. Insert the capacitor to be tested into the capacitance jack.
2. Set the rotary switch to an appropriate measurement position in the F range.
3. Connect the test leads across with the object being measured. The measured value shows on
the display.
Note:
• For testing a capacitor with polarity, connect the red test lead to the anode and the black test
lead to the cathode.
• When the tested capacitor is shorted or the value is overloaded, the LCD displays '1'.
• To minimize the measurement error, the testing lead should be as short as possible.
• It is normal to take a longer time when testing a>10µF high capacitor value.
E. Diode measurement
Disconnect circuit power and discharge all the high voltage capacitors before measuring diodes. Do
not attempt to input voltages higher than DC 60V and AC 30V rms to prevent any damage and to
avoid harms to yourself.
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, connect the meter as follows:
Insert the red test leasd into the W terminal and the black test lead into the COM terminal.
1.
2. Set the rotary switch to diode test.
3. For forward voltage drop readings on any semiconductor component, place the red test lead
on the component's anode and the black test lead on the component's cathode. The measured
value shows on the display.
OPERATING MANUAL
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