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4. TROUBLE SHOOTING
4.11 Keypad backlight trouble
Key Pad Back Light is on as below :
Key pressing → STn8810 commend MSM6275 lighting the Key LED →
MSM 6275 KPD_DRV_N go to Low → LED On (Key Pad LED controlled by PM6650)
VA400 (KPD_DRV_N)
LD101~108 and R106~114 (Sub)
LGE Internal Use Only
Start
Key press
NO
AP_+VPWR is OK?
Yes
Signal KPD_DRV_N
is Low?
Yes
Yes
Only Sub board LED
is not work?
NO
Yes
Some LED
is not work?
NO
NO
Work well?
Yes
En d
R400 (AP_+VPWR)
- 118 -
Check device short :
LD400~407 and R402~412 (Main)
LD101~108 and R106~114 (Sub)
NO
Change the main board
Check connection
between Main and FPCB
and between FPCB and Sub
Check device open :
LD400~407 and R402~412 (Main)
LD101~108 and R106~114 (Sub)
Change the main & Sub board
LD400~407 and R402~412 (Main)
Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
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