Samsung SCH-A302 Service Manual page 8

SCH-A302
Trouble Shooting
1-3. Abnormal Backlight Operation
Press any button on the phone
'L' level outputted
from U501 pin1?
'L' level outputted
from U501 pin2?
Backlight LED on
1-4. Abnormal Key Data Input
Check initial status
Scanning signals
outputted from U609 pins C2,
A3, E4, D3, C1?
Y
Y
Y
END
SAMSUNG Proprietary-Contents may change without notice
Check U501 pin1 and its neighboring
N
circuits. Replace if required.
Check U501 pin1 and its neighboring
N
circuits. Replace if required.
Check keypad dom switch.
N
Replace if required.
2-3