VOLTCRAFT VC-140 Bedienungsanleitung Seite 31

1. Connect the black instrument lead to the COM jack and the red
instrument lead to the V/Ohm jack.
2. Set the rotary switch to "-> I-/o".
3. The displayed value of the diode test always refers to the forward
voltage of a Si-semiconductor section (Silicon p-n junction). If you
carry out a continuity test and the resistances are lower than
approx. 70 Ohm, there will sound an acoustic signal. Even if the
diodes have been short-circuited (defective), this acoustic signal
can be heard.
red black
instrument lead instrument lead
conducting direction
Now connect the test probes to the measuring object, an idle semi-
conductor section, the red test probe to the anode, the black test
probe to the cathode (usually this is marked by means of a coloured
ring, point or something similar).
If you test a diode section in conducting direction, you will measure
a voltage that reaches from approx. 0,6 V (Silicon) to 3 V (or from
600 mV to 3000 mV) provided that the diode section is not defec-
tive.
If you now switch the test probes, that is to say connect red to the
cathode and black to the anode, you will test the so-called non-con-
duction direction of the diode section.
If the sign "1." for Overload = overflow is displayed, the diode is
working properly. If, however, a "voltage value" is displayed, the
measuring object has either been connected improperly or it is
defective.
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red black
instrument lead instrument lead
non-conducting direction
Each of the five direct voltage ranges DCV has an input resistance
of 10 MOhm.
If the sign "-" appears in front of the measuring value at the direct
voltage measurement, the measured voltage is negative (or the
instrument leads have been mixed up).
Note!
Due to the fact that the measuring input is very sensitive, it may
occur with instrument leads that are not connected to any mea-
suring object that the display indicates any measuring values.
This "phenomenon" is normal and disappears as soon as you
start to carry out measurements.
B Alternating voltage measurement
Never exceed the max. admissible input quantities. Max. 600
VDC or VACrms with galvanic separation from the network in
the overvoltage category I or max. 300 VDC/ ACrms in the over-
voltage category II.
Do not touch any circuits or circuit elements if you are measu-
ring voltages that exceed 25 VACrms or 35 VDC.
Proceed as follows to measure alternating voltages:
1. Connect the red instrument lead to the V/ Ohm jack and the
black instrument lead to the COM jack.
2. Set the desired voltage measuring range with the rotary switch. If
you measure alternating voltages (V~), you can select among 2
measuring ranges (200V and 600V).
3. Connect the test probes to the measuring object (load circuit,
etc.).
4. The polarity of the measuring value and the actual measuring
value are indicated in the big display.
Each of the two alternating voltage ranges has an input resistance
of approx. 5 M ߟ, parallel to < 20 pF (AC coupled).
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