Keypad Backlight Trouble - LG G5500 Manual

4.11 Keypad Backlight Trouble

Block Diagram
Backlight Operation
• The keypad LED backlight is controlled with KEY_LED signal.
• KEY_LED signal from ABB.
• The LEDs are forward biased and turned on.
Trouble Shooting Setup
• Connect PIF-UNION to the phone, and power on.
• Enter the engineering mode.
• Go to menu "Baseband → Backlight → Keypad on"
Trouble Shooting Procedure
• Check the soldering of components
• Check the KEY_LED signal
• Check LEDs
Check Points
• KEY_LED signal
• LEDs
• Operation of FPCB
Check
soldering !
-70-
Check
KEY_LED signal
R113,R114