Asus VB191T Service Manual page 45

19" LCD Color Monitor
8.2.2 Power/Inverter Board
1.) No power
Check CN902 pin4, 5 = 12V
NG
Check AC line volt 110V or 220V
OK
Check the voltage of C905 (+)
OK
Check start voltage for the pin8 of IC901
OK
Check the auxiliary voltage is bigger than
10V and smaller than 20V
Check IC901 pin6 PWM wave
OK
Check IC903, IC904, Q901, ZD921, ZD922, D915, D916
NG
NG
NG
NG
OK
Check AC input
Check bridge rectified circuit and F901 circuit
Check R904, R932, R933 and Change IC901
1) Check IC901
2) Check R909, D901 circuit
NG
Check IC901
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ASUS VB191T&S