4.8 Checking the control circuit of vertical sync pulse for VGA
Check the vertical sync signal on P 302
pin14 TTL level
Fa ilu r e Po int:
VGA video cables is failure.
Check the vertical sync
signal on I306 pin90 TTL level
NG
OK
Fa ilu r e Po int:
1. Printed wire is open between P302 pin14 and I306
pin90.
2. FB312 and R 322 m ay 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
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