NEC AccuSync LCD71VM - Checking the Horizontal Sync Pulse Control Circuit; Checking the Sync Signal Interface Circuit

6-8
6. Checking the Sync Signal Interface Circuit
6.1 Checking the Horizontal Sync Pulse Control Circuit
Check the horizontal sync signal on U402 pin 1 a
t
TTL level.
NG
OK
Failure point
1) No separate sync or sync output by (Confirm
the host, output the sync signal.)
2) Video cable may have failed.
3) Printed wire broke between P401 pin 13 and
U402 pin 1.
4) B401 or R415. open.
5) U402 failure.
Check the horizontal sync signal on U405 pin 101 a
TTL level.
Procees section 7 “Checking the scaling IC
movement”.
NG
OK
Failure point
U405 failure.