Philips HTS3541/05 Service Manual page 26

keys do not work
keys do not work
Go
Check voltage +5V on Front Board U135
PIN38
Yes
Check Front Control Board signals at XP2
Pin8 VSCLK,Pin7 VSDA,Pin6 VSTB
Yes
Replace U135 on Front Board
5-2
No
Fix the connection XP2 to
Main Board
No
Replace U4 on Main Board, or
replace Main Board
Trouble shooting Chart
XP8 on