AOC LM-729 Service Manual page 37

LM-729 Service Manual
2.PANEL-POWER CIRCUIT
check R203 should have response from 0V to 5V
When we switch the power switch from on to off
OK, R86 have response
Measured the Q302 pin 7,8= 5 V?
OK
3.I
NVERTER Control Relative Circuit
Measured the inverter connector CN11
pin 2 on/off control=5V (on)
pin4 PWM signal control dim 0V-5V
Replace Power board to new-one, and
Check the screen is normal ??
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NG, no Voltage
OK
NG, still no screen
OK
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Check the PPWR panel power relative circuit,
NG
Q5, Q2(pin7,8)
In normal operation, when LED =green, R203
should =0 v,
Replace Q302 ( N-MOS, SI993
NG
Check the Bklt-On relative circuit, R113, R115, R117,
In normal operation, when LED =green,
R405 Bklt-On should =5 v,
If Bklt-On no-response when the power switch turn on-off,
Replace U4 GM5126/2126
NG
Replace Power board
& Re-do white balance
Page 38 of 61
Rev: A
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