21
Subject to change without notice
In-circuit tests are possible in many cases. However, they
are not well defined. This is caused by a shunt connection of
real or complex impedances - especially if they are of relatively
low impedance at 50Hz - to the component under test, often
results differ greatly when compared with single components.
In case of doubt, one component terminal may be unsoldered.
This terminal should then be connected to the insulated
COMP. TESTER socket avoiding hum distortion of the test
pattern.
Another way is a test pattern comparison to an identical circuit
which is known to be operational (likewise without power
and any external connections). Using the test prods, identical
test points in each circuit can be checked, and a defect can
be determined quickly and easily. Possibly the device itself
under test contains a reference circuit (e.g. a second stereo
channel, push-pull amplifier, symmetrical bridge circuit), which
is not defective. The test patterns show some typical displays
for in-circuit tests.
Ω
µ
Ω
Ω
Ω
µ
Ω
