Checking The Interface Circuit Of Sync Signal - HP WF1907 Service Manual

4.7 Checking the interface circuit of sync signal

4.7.1 Checking the control circuit of horizontal sync pluse for VGA
Check the horizontal sync signal on P302 pin 13 TTL
Check the horizontal sync signal on I306 pin 89 TTL
Failure Point
Process "Checking the resolution change IC movement"
section.
4.7.2 Checking the control circuit of vertical sync pluse for VGA
Check the vertical sync signal on P302 pin 14 TTL
Check the vertical sync signal on I306 pin 90 TTL
Failure Point
Process "Checking the resolution change IC movement"
section.
level.
NG
OK
level.
NG
OK
level.
NG
OK
level.
NG
OK
Failure Point
VGA Video cable is failure.
Failure Point
1) Printed wire broke between P302 pin 13 and
I306 pin 89.
2) FB311, R321 is open.
3) R324, C328 is short.
Failure Point
VGA Video cable is failure.
Failure Point
1) Printed wire broke between P302 pin 14 and
I306 pin 90.
2) FB312, R322 is open.
3) R323, C327 is short.
Page 20