Front Circuit(Digitron & Key) - NAD T512C Service Manual

4. Front Circuit (Digitron & key)
START
Power on.
LED ON?
YES
Is Digitron on normally?
YES
Do all the
buttons work
normally?
YES
Check waveform of
Check and replace
R903,R912, R904, R905,
R941, R906, R907.
Does remote control
work normally?
YES
Complete repairing Front B/D.
NO
Is oscillation of
X901 normal?
YES
NO
Check waveform
of IC901 Pin 7.
CD YES
NO
Is waveform of IC901
Pin 21 normal?
YES
NO
IC901 Pin 14.
YES
Solder defective parts again.
NO Does pulse
waveform of RC901 Pin 1
appear?
YES
Is IC901
Pin 17 connected to
RC901 Pin 1 ?
YES
Replace IC901.
YES
NO
Check Power.
NO
Replace IC902.
NO
Check waveform
of IC901 Pin 14.
Replace IC901.
Check waveform
of IC901 Pin 18, 19.
Replace LED913.
NO
Is RC901 Pin 2 5V?
YES
Replace RC901.
YES
Re-solder.
YES
3-7
NO
YES
Solder Key part.
NO
YES Replace IC901.
NO
Solder defective parts
Recheck