Key Sense Trouble - LG U8290 Service Manual

4. TROUBLE SHOOTING

4.13 Key Sense Trouble

Key Sense sequence of U8290 is :
Default condition ROW(0-4) is 2.6V → Press the key → Corresponding row(x) go to 0V → Key sensing
CN2
ROW[0-4]
COL[0-5]
Change the side key
Work well?
Check the CN2
ROW(0-4) is 2.6V?
Check the CN300?
Change the Main board
RA1(ROW[0-4])
R4
Start
pcb
Yes
NO
NO
YES
NO
YES
Yes
NO
- 112 -
End
Change the Key pcb
Check RA1 And R4
Change the Main board
CN300