Keypad Backlight Led Trouble Shooting - LG L240 Service Manual

4.14 Keypad Backlight LED Trouble Shooting

z Keypad backlight LED Operation scheme is shown below.
VBAT
R517 10K
KEY_LED_EN
R517
Q501
z Backlight operation
- Keypad backlight LED is controlled with KEY_LED_EN signal
- KEY_LED_EN signal from DBB(U102)
- The LEDs are forward biased and turned on
z Check Point
- VBAT level ( 3.35 ~4.2V)
- LEDs
- Q501
3
Q501
2
2SC5585
1
R518
- 83 -
4. TROUBLE SHOOTING