IBM L150 Service Manual page 34

2.PANEL POWER CIRCUIT
check R507 should have response
from 0V to 3.3V
When we switch the power switch from
on to off
Measured the Q501 pin 3= 3.3 V?
OK
3.INVERTER Control Relative Circuit
Measured the inverter connector
CN504
pin1 on/off control=3.3V (on)
pin2 PWM signal control dim 0V-5V
Replace power board to new-one
and check the screen is normal?
OK
OK
OK
NG, still no screen
NG
Check the PPWR panel power relative circuit, Q501, Q502
In normal operation, when LED =green, R507 should =0 v,
If PPWR no-response when the power switch
Turn on and turn off, replace the U203-GM5120/2120
NG, no Voltage
NG
Check the Bklt-On relative circuit, R357, R358,
In normal operation, when LED =green,
R357 Bklt-On should =5 v,
If Bklt-On no-response when the power switch
turn on-off, Replace U203 GM5115/2115
NG
Replace Power board
& Re-do white balance
34
Check U202 pin 2= 3.3V
Yes
Replace Q501 ( AO3401)
IBM 15" Service Manual