Main Keypad Backlight Troubleshooting - LG TracFone LG840G Service Manual

4.13 Main Keypad Backlight Troubleshooting

MAIN Key Pad Back Light is on as below :
Key pressing -> TP1 go down low (below 0.8v) -> MAIN Key Backlight LED On
Change the Main board
TP2
LGE Internal Use Only
START
Key press
+VPWR(TP2) is
above 3.2V?
Yes
+VPWR
TP2
R606 47
LD601
R607 47
LD602
R608 47
LD603
TP1
TP1
No
Check battery
KEY_BACKLIGHT
VA608
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4. TROUBLE SHOOTING
Only for training and service purposes