Checking The Vertical Sync Pulse Control Circuit - NEC AccuSync LCD51VM Series Service Manual

6.2 Checking the Vertical Sync Pulse Control Circuit

Check the vertical sync signal on U402 pin 5
at TTL level.
NG
OK
Check U405 100 pin is TTL
NG
OK
Proceed section 7 "Checking the Scaling IC
Operation".
Failure point
1) No separate sync output signal from the host.
(Check the host.)
2) Video cable may have failed.
3) Printed wire broke between P401 pin 14 and
U402 pin 5.
4) B402 or R16 open.
5) U402 failure
Failure point
1) U402 failure.
2) R480 open.
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