6-9
6.2 Checking the Vertical Sync Pulse Control Circuit
Check the vertical sync signal on U402 pin 5
at TTL level.
NG
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
OK
Proceed section 7 “Checking the scaling IC
movement”.
