JVC KD-S12 Service Manual page 27

5.5 Signal processing section
YES
Is the sound output from
both channels (L, R)?
NO
YES
No sound from either
channel.
NO
Compare the L-ch and
R-ch to locate the
defective point.
Normal
YES
Is 9V present at pin 31
of IC301?
NO
YES Check the connections
Is 9V present at pin 10
of IC901?
NO
Check IC901 and its
peripheral circuits.
Is the audio signal
(including sampling
YES
output components)
output to pins 1 and 7 of
IC151 during playback?
NO
Check IC151 and its
peripheral circuits.
between pin 31 of IC301
and pin 10 of IC901.
Is the audio signal output
at pin 3 and pin 30 of
IC301 during playback?
NO
Check IC301 and its
peripheral circuits.
NO
Check the power
amplifier IC321.
(No.MA216)1-27