Keypad Back Light Trouble - LG KC780 Service Manual

5.10 Keypad back light trouble

Check Points
-Signal path is connected well
-Analog SW is working properly
KP_IN(5:6)
KP_OUT(0:4)
B4
VOUT
D2
LED1
C2
LED2
C1
LED3
B1
LED4
B2
LED5
A2
LEDFL
U700
F5
SBIAS
BD6095GUL
F3
SSENS
E4
GC1
E3
GC2
F2
LDO1O
E2
LDO2O
D1
WPWMIN
D3
FLASHCNT
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
DOWN
R703 680
KP_IN(5)
KP_IN(6)
KP_OUT(0)
R705 680
KP_OUT(1)
R706 680
KP_OUT(2)
R707 680
KP_OUT(3)
R708 680
KP_OUT(4)
MLED
MLED1
MLED2
MLED3
MLED4
MLED5
SUB_KEY_BL
UPPER_KEY_BL
LCD_PWM
FLASHCNT
TP700
C709
2.2u
Slide Key Matrix and LEDs on KEY PCB
CLEAR MENU
SEND LEFT
VBAT
R709
TP4
0
C710
R711 R712
1u
47 47
LD700 LD701
TP1
3
R714 12K
Q700
2
KTC4075E
1
R715
C711
R716 R717
12K 1u
10 10
- 87 -
5. TROUBLE SHOOTING
SELECT OK
RIGHT UP
R710
MLED
DNI
R713
SUB_KEY_BL
DNI
LGE Internal Use Only