5-1 Trouble shooting Chart
LED No display on Front Control Board
LED No display on
Front Control Board
Go
Yes
Refer to CON501 on Power Board
No
Check whether U11 and U10 work
good or not? And fix it or replace the
main board.
No
Replace MCU U8 on Main Board, or
replace the Main Board
No
Check the XP15 ON Front Control Board,
signals at Pin5, 6, 7 arrive the IC U301
PIN2,3,4
No
Yes
Yes
Yes
Correct connection
No
Yes
Replace U301 or LED
Check every supply voltage on Main Board
whether normal or not.
(XP4 PIN4&PIN5:+12V)
Check v5V on main Board at XP9
PIN16: +5V
Check the power key S608, open/closed key
S612, source keyS611 and other key on
Front Board whether work normally or not
Check Front Control Board signals at XP15
Pin5 VSTB, Pin6 VSCLK, Pin7 VSDA
Check whether bad solder exists on XP15
on Front Control Board and U301 or LED
Yes
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