Samsung SCH-A399 Service Manual page 29

5-1-4 Abnormal Key Data Input
Check initial status.
Scanning signals
outputted from U100
scan 0~5 Keysense
0~3
Normal Key data
input?
YES YES YES YES
END
5-4
NO NO NO NO
YES YES
YES YES
NO NO NO NO
Check MSM board U100
Replace the Keyboard.
Trouble shooting