Jvc lt-23d50bk have a good picture on the bbc channels then it goes after a few seconds while watching in digital

SOURCE: Picture blacks out after a few seconds after turning on the tv

Anytime an LCD has a shade of pink, that means the CCFL lamps are about to go out. Now that you have a black screen, I'd say you just need some new bulbs.

SOURCE: picture for 1 second then screen goes blank but still have audio

i have taken the tv to repair shop a circut board has went on it

SOURCE: Nikkai A75HQ Digital Freeview Receiver

I'm using an attenuator 3db/5-1000Mhz - I get all channels. Without I got 100% strength,0% quality. hope it helps

SOURCE: No freeview bbc channels

just solved the problem
with the variable attenator fitted i did a rescan still didnt work
but when i did a rescan to the restore factory settings it now works

SOURCE: JVC LT 42x688 no picture just sound

Sorry, this has no easy fix. The good news is you do not need an LCD Panel. The bad news is the Video Processor has a problem.
This TV has x3 Boards. The one you should replace first is the one in the middle. If this doesn't fix it, try the one on the right. The Part #s are on the Boards if you wanna try ebay.