Conrad VC-222 Bedienungsanleitung Seite 10

D Resistance measurement
Ensure that all circuit components, circuits and
assemblies and other objects to be measured are
completely voltage-free.
To record a measured value, proceed as follows:
1. Connect the black test lead with the COM socket and the red
test lead with the V/Ohm socket.
2. Position the rotary switch to "½"; range-switching occurs auto-
matically, i.e. the measuring instrument matches itself auto-
matically to the measured value.
3. Check the test leads for continuity by connecting both test
probes together. The indication should be 0.1 or 0.2 Ohm.
4. Now connect the measuring probes to the object to be
measured.
Note!
When resistance measurements are performed, take care that
the measurement points which are to be contacted by the test
probes are free from dirt, oil, solder flux or similar. Such condi-
tions can distort the measured value.
With resistances greater than approx. 1 MOhm, the display can
take some time to become stabilised. Should "O.L" appear in
the display, the measurement range has been exceeded or the
circuit being measured is open-circuited.
E Diode test
To measure diodes or other semi-conductor paths, proceed as
follows (observe without fail the following illustrations):
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1. Connect the black test lead to the COM socket and the red test
lead to the V/Ohm socket.
2. Position the rotary switch to "->I-".
3. With diode test, the indicated value refers to the forward voltage
of a silicon semiconductor path (Si P-N junction).
black
red
measuring measuring
Conducting direction
Now connect the test probes to the measurement points, an unpo-
wered semiconductor circuit, with the red probe to the anode and
the black probe to the cathode (these usually being indicated by a
coloured ring, spot or similar).
If you test a diode path in the conducting direction, you will measu-
re a voltage of from approx. 0.6 V (silicon) to 3 V (i.e. 600 mV to
3000 mV), provided that the diode path is not defective.
If the test leads are interchanged, i.e. red to the cathode and black
to the anode, then the non-conducting direction of the diode path
is checked.
If "O.L" for overload is displayed, then the diode is in good conditi-
on. If on the contrary a "voltage value" is displayed, then either the
path being measured is incorrectly connected or is defective.
During diode testing, make sure that the diode and
any circuit into which it may possibly be built, is ab-
solutely voltage-free. All capacitors present must
be discharged.
red black
measuring
measurin
Blocking direction
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