Acer AT1945 Service Manual page 34

No Power (No LED indicator)
Check CN902 pin10,11 = 12V
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
OK
Check IC901 pin5 PWM wave
OK
Check T901, Q903, D906, D904, D912, ZD920, ZD902, IC903
NG
Check AC input
NG
Check bridge rectified circuit and F901 circuit
NG
NG 1) Check IC901,D902,C908
2) Check IC902 OVP circuit
NG
Check IC901
34
Check R904, R905 and Change IC901