AOC P/N : 41A50-144 User Manual

Page 17

PANEL-POWER CIRCUIT

NVERTER Control Relative Circuit

OSCILLATOR BLOCK

U200-DATA OUTPUT

OK,R225 have response

check R225 should have response from 12V to 0V
When we switch the power switch from on to off

Check the PPWR panel power relative circuit,
R223, 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-GMZAN1

Measured the U202 pin 5,6,7,8= 5 V?

Replace U202 ( Nmos, SI9933)

NG, no Voltage

Replace INVERTER-module
& Re-do white balance

Replace INVERTER to new-one, and
Check the screen is normal ??

Measured the inveter connector CN303
Pin 1=12V, pin 3 on/off control=5V (on)

NG, still no screen

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

Measured U201 Oscillator output R215= 50mhZ ?

Replace Oscillator U201

NG,no transition

OK, has transition

Measured X300 Crystal output R340= 20mhZ ?

Replace Crystal X300

NG,no transition

Measured PCLK(L207)
PVS,PHS (pin 73,74 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)

Replace GMZAN1 (U200) or replace
MAINBOARD.

NG , no transition

If MainBoard being replace , please
do the DDC – content reprogrammed

Check U202 pin 1,2,3,4= 5V

Check U304 relative circuit.(R905,T300..)