Service manual

4.8 Checking the control circuit of vertical sync pulse for VGA
Check the vertical sync signal on P302
pin14 TTL level
Fa ilu r e Poin t:
VGA video cables is failure.
Check the vertical sync
signal on I306 pin90 TTL level
NG
OK
Fa ilu r e Poin t:
1. Printed wire is open between P302 pin14 and I306
pin90.
2. FB312 and R322 may be open.
3. R323 and C327 may be short.
4. D305, D306 is short.
NG
OK
Proceed ‘Checking the resolution change IC
movement’ section
7. Troubleshooting (continued)
21
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ACER AL1716W