Key Sense Trouble ( Keypad ) - LG KF310 Service Manual

4.4 Key sense trouble ( KEYPAD )

Key Sense sequence of KF310 is :
Default condition ROW(0-3) is 2.7V
→
Scan pulse( Col => Row )
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Only for training and service purposes
→
Press the key
→
MSM sense what key pressed.
start
Check RA 400 0, R401 4
Row(0~ 4) is 2. 7V
YES
Change the Dome Sheet
Work well ?
YES
Check short the Short ,
Row 0~ 4, COL 0~ 4
Some Point is short ?
YES
Short Point clear
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4. TROUBLE SHOOTING
→
Corresponding ROW(x) and COL(x) go to 0V
NO
Change Main Board
NO
Change Main Board
NO
Change Main Board
LGE Internal Use Only