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4.11 Keypad Backlight Trouble
Block Diagram
Backlight Operation
• The keypad LED backlight is controlled with LEDB signal.
• LEDB 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 → LED → Backlight → Keypad on"
Trouble Shooting Procedure
• Check the soldering of components
• Check the LEDB signal
• Check LEDs
Check Points
• LEDB signal
• LEDs
Check
soldering !
-66-
Check
KEY_LED signal
R422,R423
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