Keypad Backlight Troubleshooting - LG CU405 Service Manual

4.11 Keypad Backlight Troubleshooting

Key Pad Back Light is on as below :
Key pressing → KYBD_BACKLIGHT go to 0V → Main LED On
Start
Key press
Signal +VPWR is above 3.2V?
VA614 is 0V ?
Change the Main board
VA614
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Only for training and service purposes
NO
Yes
NO
Yes
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4. TROUBLE SHOOTING
Check battery
Yes
Change the Main board
VPWR
LGE Internal Use Only