Trouble Shooting; Main Board - AOC LM-729 Service Manual

LM-729 Service Manual

8.2 Trouble Shooting

8.2.1 Main Board

1.NO SCREEN APPEAR
Measured CN11 pin5 = 12 V?
Measured CN11 pin 9/10= 5V?
Measured U8 pin 2= 3.3V?
Measured U9 pin 2= 2.5V?
Yes, all DC level exist
Disconnected the Signal cable( Loose the
Signal cable ),Is the screen show "Cable Not
Connected" ?
No, nothing is show
Connected the Signal cable again,
Check LED status.
Led Green
Check the Wire-Harness from CN2
Check Panel-Power Circuit Block
Check U4 Data-output Block
Replace Power board and Check
Inverter control relative circuit
Re-do White balance adjust
Note: 1. if Replace "MAIN-BOARD" , Please re-do "DDC-content" programmed & "WHITE-Balance".
2. if Replace "Power Board" only, Please re-do " WHITE-Balance"
Led Orange
OK,Wire tight enough
OK,Panel Power OK
OK, U4 data OK
Yes. there have OSD show
Connected the Signal cable again,
Check LED status.
Check Power switch is in Power-on
status , and check if Power switch had
been stuck ?
OK, Keyboard no stuck
Measured RGB (R15,R17,R24) H,V Input at
U4 pin 176,177 ,was there have signal ?
Check digital signal from CN1
OK,input Normal
Measured Crystal X1(14.318MHz)
Replace U203 (GM5126/2126)
OK
Rev: A
Check Correspondent component.
Is there any shortage or cold solder?
Led orange
NG
OK,clock
Led Green
Replace U6
Flash Rom
Check Correspondent
component short/open
( Protection Diode )