Optima L903AD+ Service Manual page 42

19" LCD Color Monitor
8.2.2 Power/Inverter Board
(1) No power
Check CN902 pin2/4 = 12V
NG
Check AC line volt 110V or 220V
Check the voltage of C905 (+)
Check start voltage for the pin3 of IC901
Check the auxiliary voltage is bigger than
10V and smaller than 20V
Check IC901 pin8 PWM wave
Check Q902, Q903, D910, D911, ZD901, IC902,IC903 and T901
NG
OK
OK
NG
OK
OK
OK
Check AC input
NG
Check bridge rectified circuit and F901 circuit
Check R906, R907 and Change IC901
NG
1) Check IC901
2) Check IC901 over current protect circuit
NG
Check IC901
42
Optima L903AD+