Lenovo LXM-WL19CH Service Manual page 34

19" LCD Color Monitor
8.2.2 Power/Inverter Board
1.) No power
Check CN902 pin1,2 = 12V
NG
Check AC line volt 110V or 220V
OK
Check the voltage of C907 (+)
Check start voltage for the pin6 of IC901
Check the auxiliary voltage is bigger than
10V and smaller than 20V
Check IC901 pin5 PWM wave
Check Q903, D901, D904, ZD904, ZD908, IC902,IC903 and T901
NG
OK
NG
OK
OK
OK
Check AC input
NG
Check bridge rectified circuit and F901 circuit
Check R931, R904, R938 and Change IC901
NG
1) Check IC901
2) Check IC901 over current protect circuit
NG
Check IC901
34
Lenovo LXM-WL19CH