LG KE520 Service Manual page 109

4. TROUBLE SHOOTING
z MAIN KEY Backlight LED Trouble
Is the Voltage level VBAT
Check the MAIN_KEY_BL_EN(U103)
Is MAIN_KEY_BL_EN a High?
LD600~609(Main PCB)
Backlight will work properly
LGE Internal Use Only
START
3.35 ~4.2?
YES
YES
Q600(Main PCB) is
Working?
YES
Are all LEDs
Working?
YES
- 110 -
NO
Charge Battery
NO
Check the condition.
If problem, Replace U103(DBB)
NO Check the condition of Q600
If problem, Replace Q600
NO
Check the soldering of each
Resistor or Replace LEDs not
working.
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