Sony KD-55A8F Service Manual page 62

5.0 Key Switch Buttons Error
Side key buttons error
Check harness
OK
connection between
B-board and switch
module
NG
OK
Change harness
between B-board to
switch module harness
NG
OK
Change switch module
NG
Main device issue
Change B-board
Harness connection issue
B-board to switch module
harness issue
Switch module issue
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SYS SET