LG 42LH50 T-CON BOARD CHECKING METHODS

Use LD-1 to determine if the boot up sequence of the T-Con board is OK.  This LED will light bright blue shortly after after power is applied, and then will go out in about 40 seconds.  This assists the back lights in firing.
On the T-Con board there is a regulator, located very near to the main IC [U11]/  Check it voltage.

U 11 Location on T-Con board

Check the SMD type fuse {F-11}. [[On T-Con board]

Fuse F-11 position on T-Con board.  If this fuse is found open, T-Con might be faulty.  [Short circuit]