LG F3000 - Key Backlight LED Trouble

4. TROUBLESHOOTING
- 84 -
4.11 Key Backlight LED Trouble
(GPIO_22)
KEY-PAD BACK-LIGHT
C729
C741
1u
27p
2 56
31 4
IMX9T110
Q701
91
R726
VBAT
SP710
C737
1u
SP705
330
R724
SP704
SP701 SP702
LD707
AOT-0603P-B01A-VC
C734
1u
AOT-0603P-B01A-VC
LD704
R725
330
SP711 SP714SP708SP706 SP707SP703
AOT-0603P-B01A-VC
LD702
R723
150
C728
1u
330
R727
C739
1u
R728
330
91
R718
91
R720
LD714
AOT-0603P-B01A-VC
VBAT
10R738
LD712 LD711
AOT-0603P-B01A-VC
C727
AOT-0603P-B01A-VC
LD709
1u
AOT-0603P-B01A-VC
C738
1u
R717
150
C740
27p
1u
C730
AOT-0603P-B01A-VC
LD706
12K
R732
R719
91
1u
C733
LD701
AOT-0603P-B01A-VC
C731
1u
10R736
1u
C726
LD705
AOT-0603P-B01A-VC
150
R722 R721
150
1u
C732
R730
330 330
R729
C735
SP712
1u
SP709
AOT-0603P-B01A-VC
LD708 LD703
AOT-0603P-B01A-VC
C736
1u
12K
R737
AOT-0603P-B01A-VC
LD713
AOT-0603P-B01A-VC
LD710
SP713
KEY_BACKLIGHT
BACKLIGHT WILL
WORK PROPERLY.
START
Is the voltage level VBAT
3.6-4.2V?
No
Are all LEDs LD701~LD714
working?
No
Check the soldering of each R or replace LEDs not working.
Yes
Charge battery
No
Check the condition of Q301. If problem, Change Q301
Yes
Q301 is working?
Yes
TEST POINT
Checking Flow
CIRCUIT
Figure 4-11
Main PCB