Keypad Backlight Trouble - LG CG225 Service Manual

4.12 Keypad Backlight Trouble

Block Diagram
KEY BACKLIGHT
VBAT
Backlight Operation
• The keypad LED backlight is controlled with LEDB signal.
• Keypad_Main signal from DBB.
• 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 → LED → Backlight → Keypad on"
Trouble Shooting Procedure
• Check the soldering of components
• Check the LEDB signal
• Check LEDs
Check Points
• LEDB signal
• LEDs
LEDB
R340
R341
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4. TROUBLE SHOOTING
20
20
VA304
Check
KEY_LED signal
R341,R340