LG KS20 - Keypad Backlight Troubleshooting

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Only for training and service purposes
4. TROUBLE SHOOTING
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4.15 Keypad Backlight Troubleshooting
Key Pad Back Light is on as below :
Key pressing -> KPD_DRV_N go to 0V -> Key Backlight LED On
Start
Check battery
NO
Yes
Key press
Change the Main board
or Check the Key FPCB
Yes
NO
+VPWR is above 2.6V?
KPD_DRV_N is 0V ?
Yes
VPWR
KPD_DRV_N
Check an U100 SMT status
by X-ray
Exchange U100 or
Change the Main board
And Retest
Power Keypad LED
PRSB6.8C
D107
SSC-TWH104-HLS
LD104
VPWR
SSC-TWH104-HLS
LD101
LD102
SSC-TWH104-HLS
R101100ohm
SSC-TWH104-HLS
LD103
R103100ohm
R102100ohm
100ohm
KPD_DRV_N
R100