Conrad VC444 Bedienungsanleitung Seite 9

D Resistance measurement
Ensure that all circuit components, circuits and as-
semblies and other objects to be measured are
completely voltage-free.
To perform a resistance measurement, proceed as follows:
1. Connect the black test lead to the COM socket and the red test
lead to the V/Ohm socket.
2. Set the rotary switch to the required measurement range (200
Ohm, 2000 Ohm, 20 kOhm, 200 kOhm or 20 MOhm).
3. Then connect the test probes to the completely voltage-free ob-
ject to be measured.
Note!
When resistance measurements are performed, ensure that the
measurement points which are to be touched with the test pro-
bes are free from dirt, oil, solder flux or similar. Such conditi-
ons can distort the measured value.
With resistances greater than approx. 1 MOhm it can be that
the display takes some time to stabilise. Should "1." appear in
the display, the measurement range has been exceeded or the
circuit being measured is open-circuit.
E Diode test
For the measurement of diodes or semiconductor paths, proceed
as follows (observing without fail the following illustrations):
1. Connect the black test lead to the COM socket and the red test
lead to the V/Ohm socket.
2. Set the rotary switch to "->I-".
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3. With diode test, the indicated value refers to the forward voltage of
a silicon or germanium semiconductor path (Si or Ge PN-junction).
red black
measuring measuring
Conducting direction
Now connect the test probes to the points to be measured in an
unpowered semiconductor circuit, with the red probe to the anode
and the black probe to the cathode (usually this being indicated by
a coloured ring, spot or similar ).
If a diode path is tested in the conducting direction, a voltage of
from approx. 0.3 V (germanium) or 0.6 V (silicon) to 3 V (i.e. 300/600
mV to 3000 mV) will be measured provided that the diode path is
not defective.
When the test probes are reversed, i.e. red to the cathode and
black to the anode, then the non-conducting direction of the diode
path is checked.
If "1." (normally meaning overload) is displayed, the diode path is not
defective. If on the contrary a voltage value is displayed, then either
the object 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.
black
red
measurin measuring
Blocking direction
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