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LGE Internal Use Only
Copyright © 2009 LG Electronics. Inc. All right reserved.
Only for training and service purposes
4. TROUBLE SHOOTING
4.18. Main Key Backlight LED Trouble Shooting
z
Keypad backlight LED Operation scheme is shown below.
z
Backlight operation
- Keypad backlight LED is controlled with LED_BC signal
- LED_BC signal from DBB(U100)
- The LEDs are forward biased and turned on
z
Check Point
- VBAT level ( 3.35 ~4.2V)
- LEDs
- Main key, Main, Main FPCB connection
TP1_F
TP2_F
TP1
TP2
1
0
6
R
0
1
0
0
6
D
L
T
A
B
V
0
1
1
0
6
D
L
0
0
6
R
C
_
D
E
L
_
M
U
N
1
0
0
6
R
1
0
6
R
1
1
0
6
D
L
0
0
6
D
L
C
_
D
E
L
_
I
V
A
N
A
_
D
E
L
M