6-12
8. Checking the interface circuit of sync signal
8.1 Checking the control circuit of horizontal sync pulse
Check the horizontal sync signal on U1 pin 1 at TTL
level.
NG
OK
Failure point
1) No separate sync or composite sync
output by host. (Confirm the host,
output the sync signal.)
2) Video cable may have failed.
3) Printed wire broke between CN1 pin
13 and U13 pin 30.
4) R10, R38, L14, R74 open.
5) U12 failure.
Procees section 9 “Checking the resolution change
IC movement”
NG
OK
Failure point
U3 failure
Check the hovizuntal sync signal on U3 pin 206 a
TTL level.
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