Try finding the service manual as that should call it out.
Also Sears online sometimes has exploded parts diagrams (sorry if I don't do the work here for you.)
Finally as I'm in the USA I can always ask the folk at shopjimmy.com
Can anyone tell me if the 50LN5400 has an inverter that's separate from the mainboard? i have the same problem as a lot of other people ,,, black screen with a very faint picture. If it's a separate inverter i can't seem to find an aftermarket part. I can find PLENTY of mainboards, but won't buy one if it won't fix the problem.