Prima PS-42T8, Service Manual

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2 7
3.With picture but no sound:
4. A certain channel is abnormal
4.1 No picture on AV
The sound power amplifier or peripheral
circuit has problem. Check power supply,
if the control of SHUTDOWN pin is
normal; if output short-circuited or other
problems that cause protection to work.
If the sound power board X908 is output.
The sound damaged.
Check if the second pin of sound
power amplifier input the signal.
Measure if the sound
input of current channel
of N907 is normal.
Check N907 or
peripheral circuits.
Check different levels of
circuit following input audio
signal channel.
No Yes
No Yes
No Yes
Measure if the AV input
pin of N700 have the
signal input.
Check if TV channel is
normal.
Check N903 M52797
and periphery
N700 is damaged
Check if N700
output is normal. Check N602 and
periphery circuit
No Yes
Yes
No
Yes
No