Acer SPECTRUM AL801 Service Manual page 16

PANEL-POWER CIRCUIT
check R225 should have response from 0V to 5V
When we switch the power switch from on to off
OK,R225 have response
Measured the U202 pin 5,6,7,8= 5 V?
OK
OK
I
NVERTER Control Relative Circuit
Measured the inveter connector CN303
Pin 1,2=12V, pin 3 on/off control=5V (on)
YES, still no screen
Replace INVERTER to new-one, and
Check the screen is normal ??
OK,& Re-do white balance
OSCILLATOR BLOCK
Measured U201 Oscillator output R215= 50MhZ ?
OK, has transition
Measured X300 Crystal output R340= 20MhZ ?
U200-DATA OUTPUT
Measured PCLK(L207,R603)
PVS,PHS,PDISPE (pin 73,74,43 from U200 )
Is there have any transition?
Pclk around 47MHz to 57MHZ ,
PVS=60.09Hz , PHS around 67 KHz ??(refer to
input signal=640x480@60 Hz 31k, and LED is
green)
OK
NG
NG, no Voltage
NG
NG
NG,no transition
OK
Check the PPWR panel power relative circuit,
R223,R224, Q200,U202(pin 5,6,7,8)
In normal operation, when LED =green, R223
should =0 v,
If PPWR no-response when the power switch
Turn on and turn off, replace the U200-GMZAN2
Check U202 pin 1,3= 5V
NG
Check U304 relative circuit.(D300,L906..)
Check JP202 shortage
Check the Bklt-On relative circuit, R315, Q304, R311,
In normal operation, when LED =green,
R315 Bklt-On should =0 v,
If Bklt-On no-response when the power switch turn on-off,
Replace the MCU
NG,no transition
Replace Oscillator U201
Replace Crystal X300
NG , no transition
Replace GMZAN2 (U200) or replace
MAINBOARD.
If Main Board being replace , please
do the DDC – content reprogrammed
15
Yes
Replace U202 ( Nmos, SI9953)