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Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
4. TROUBLE SHOOTING
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4.10 Key sense trouble ( KEYPAD )
Key Sense sequence of KC910 is :
Default condition ROW(0-2) is 2.7V
→
Press the key
→
Corresponding ROW(x) and COL(x) go to 0V
→
Scan pulse( Col
→
Row )
→
MSM sense what key pressed.
Check t he R701~R704 with no key press
Change the Main board
Yes
NO
Change th e DOME SHEET
Check t he R701~R704with key press
ROW(0-2) is 2.7V?
Check
R701~R704
NO
Yes
ROW(0-2),
COL(0-1) i s 0V?
Work well?
End
START
Check VA701~ VA703, VA 707~VA710
NO
YES
NO
Change SIDE KEY
Work well?
NO
Work well?
YES
YES
NO
Dome sheet
Side Key
Change th e Main board