Conrad VC940, Руководство по эксплуатации

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Model VC940: OPERATING MANUAL
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Black Red
Figure 3-5. Diode Test
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 diodes.
Use the diode test to check diodes, transistors, and other semiconductor devices. The diode test sends a current through the semicondutor junction, then measure the voltage
drop across the junction. A good silicon junction drops between 0.5V and 0.8V
To test the diode out of a circuit, set up the Meter as Figure 3-5 and proceed as follows:
1.
Insert the red test lead into the Ω terminal and the black test lead into the COM terminal.
2. Set the rotary switch to
Ω
; and press BLUE button to select measurement mode.
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 red test lead polarity is “+” while the black test lead polarity is “— “.
The measured value shows on the display.
The BLUE button cycles among resistance, continuity, and diode.
Note
z In 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.
z Connect the test leads to the proper terminals as said above to avoid error display.
z The LCD will display OL indicating either open circuit or wrong polarity connection.
z The unit of diode is volt (V), displaying the positive-connection voltage-drop value.
z Open circuit voltage approximate 2.8V.
z When diode testing has been completed, disconnect the connection between the testing leads and the circuit under test and remove the test leads away from the input
terminals.
F.
Measuring Capacitance
Black
Red
Figure 3-6. Capacitance Measurement
Warning
To ensure accuracy, the Meter inside is discharged against the tested capacitor. “DIS.C” will be shown on the display when it is under discharging, this process will
be quite slow.
To avoid damage to the Meter or to the equipment under test, disconnect circuit power and discharge all high-voltage capacitors before measuring capacitance.
Use the DC Voltage function to confirm that the capacitor is discharged.
To measure capacitance, set up the Meter as shown in Figure 3-6 and proceed as follows:
1. Insert the red test lead into the terminal and the black test lead into the COM terminal.
2. Set the rotary switch to measurement mode, the Meter may display a fixed reading which is a internal distributed capacitor value. For testing less than 10nF capacitor,
the tested value must subtract the internal distributed capacitor value to maintain the accuracy.
To improve the measurement accuracy of small value capacitors (less than 10nF), press REL with the test leads open to subtract the residual capacitance of the Meter
and leads.
Note
z The LCD displays O L indicating the tested capacitor is shorted or it exceeds the maximum range.
z Capacitors larger than 400µF take longer time. The analogue bar graph shows the time left before finishing the measurement.
z When capacitance m easurement has been completed, disconnect the connection between the testing leads and the circuit under test and remove the test leads away from the
input terminals of the Meter.
G.
Measuring Frequency / Duty Cycle