LM-522 Service Manual
27
8.2 Trouble Shooting
8.2.1 Main Board
1. NO SCREEN APPEAR
2.
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 Green
Measured CN105 pin5/pin6 =12 V?
Measured CN105 pin9/pin10 =5V?
Measured U501 pin 2= 3.3V?
Measured U502
in2=2.5V?
Check Correspondent component.
Is there any shortage or cold solder?
Yes, there is OSD show
Yes, all DC level exist
Disconnected the Signal cable (Loose the
Signal cable), Is the screen show “Cable Not
Connected”?
Connected the Signal cable again,
Check LED status.
Replace U101
No, nothing is show
Connected the Signal cable
again
Check Power switch is in Power-on
status, and check whether Power
switch had been stuck?
Led Orange
OK, Keyboard no stuck
Led orange
Led Green
Check the Wire-Harness from CN109
Measured RGB (R166, R169, R173)
H, V Input at 102 pin119,126,was
there signal?
Check Correspondent
component short/open
(Protection Diode)
NG
OK, Wire tight enough
Check Panel-Power Circuit Block
OK, Panel Power OK
Check U102 Data-output Block
Replace Power board and Check
Inverter control relative circuit
Re-do White balance adjust
OK, input Normal
Measured Crystal X101 (12MHz)
OK, clock normal
Replace U102 (NT68521A-XFG)
OK
OK
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