Sharp LL-153A Service Manual page 30

15" LCD Color Monitor
2.PANEL POWER CIRCUIT
Check R731 should have response from 0V to 5V
When we switch the power switch from on to off
OK
Measured the Q706 pin 3= 5 V?
OK
OK
3. INVERTER CONTROL RELATIVE CIRCUIT
Measured the inverter connector
CN701
Pin2 on/off control=5V (on)
Pin4 PWM signal control dim 0V-5V
Replace power board to new-one and check
the screen is normal?
OK
NG , no transition
Check the PPWR panel power relative circuit,
Mea
Q704(pin2)
In normal operation, when LED =green, R731
should =0 v,
Yes
Replace Q602 ( N-MOS, A03401)
NG, no Voltage
Check the Bklt-On relative circuit, R711, R712,
NG In normal operation, when LED =green,
R711,R712 Bklt-On should =5 v,
If Bklt-On no-response when the power switch
turn on-off, Replace U401 TSUM13AK
NG Replace Power board
& Re-do white balance
30
Sharp LL-153A