Sony KD-55A9F Service Manual page 56

4.4 NO PICTURE: @ TUNER
FOR 12V LNB Voltage Checking: @ AEP and JP
+12V_LNB Voltage Checking
OK OK
OK
Check LNB power line Check P_ON_HL signal line MOSFET
Check fuse F2801
+12V_MAIN at R495 = 12V? at CL811(R823) = 3.3V? Q408/Q409 broken
NG
NG
NG
Change the fuse
OK
Check +12V_Main at CN400 Please confirm Power
(JL401/JL411) Sequence u-com
NG
NG
Check harness between
Harness broken
B-Board and G-board
OK
Please refer G-board
troubleshooting
56
SYS SET