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9 Troubleshooting
mo
Check DC 12V line IC605, Q606.
——
Does the video pulse
MJ appear at pins 4, 6 and 9
of 1C101 on the video PCB?
Does DC 12V appear at.
No
Check signal cable
pin 11 of IC101?
and signal source.
Check clamp circuit
G101 on the main
PCB, 1C201{#22 pin)
Does the video pulse
11) appear at pins 17, 20, 26
of IC1012
13] Does the clamp signal
appear at pin 14 of 1C101?
Check contrast
control circuit
(D172, D173, D174,
D175, Q171, Q172)
Does the video amplified
pulse appear at the emittor
of OR13, 0813, 0613?
No
Does the DC voltage
appear at pin 12 of 10101?
Yes
Check contrast circuit
on main PCB D172, D173,
D174, D175,0 171, Q172.
Check cutoff control circuit.
(DR13, DG13, DB13, 1C102)
Check video amp circuit.
(D101, OR11, DR12, QRO1,
QG01, QB01, QR11, 0611,
QB11, OR12, QG12, QB12,
QR13, 0G13, OB13, OR14,
0614, OB14)
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