20 GMC-I
Messtechnik
GmbH
4.7
Test of Diodes and Transistors
The resistance measuring ranges k
x 1 and k
x 10 are also suited
for coarse functional tests of diodes and transistors. A short circuit or
an interruption of a diode and/or a diode path between base, collector
and emitter of a transistor can be found in a simply way with a "resis-
tance measurement". The polarity of a diode and the base connection
of a transistor can also be found in this way. The device under test
cannot be destroyed as the measuring voltage is 1 V at a maximum
and the measuring current. 2.2 µA or 22 µA at a maximum. From this
limitation of the measuring voltage and the measuring current it fol-
lows, however, that semi-conductors with relatively high reverse and/
or residual current, such as power diodes and power transistors, for
instance, and also rectifiers with several series-connected elements
cannot be tested as, due to the small measuring current, the difference
between the readings in forward and/or reverse direction are not
sufficiently marked.
➭
Set the range switch to position k
x 1 or k
x 10.
➭
Set switch to position „ON“.
➭
With adjustment potentiometer adjust to full scale deflection
.
➭
Connect the measuring leads to the sockets „A|
“ and „
“.
➭
Connect diode or transistor according to the following table and
measure both in forward and reverse direction.
➭
Read the resistance value on the
-scale and the voltage on the V, A
scale with the 100 part graduation.
