We have had a few LG 42LS575T led tvs in recently with all similar issues. While surprising to see such young tvs already appearing in our repair shop, it is encouraging to see that they are quite repairable and at what I believe to be at an affordable cost. 

If your tv is suffering from loosing its picture, while the sound stays on ok, then it is worth us (or any other professional tv engineer) having a look as we could save you from having to pay out for a brand new tv. Initially the picture may stay on for an hour or so before disappearing, but as the issue worsens then it may only stay on for 3 or 4 minutes.

Please see the list below for all known affected models. Please note that if you do not live in or around the Bath area then I will be unable to help with your tv repair. I can point you to your nearest tv engineer but I will not give any advice on DIY repairs.

Known affected models:
LG 42LS570T
LG 42LS570TZB
LG 42LS570TZBBEKDLJG
LG 42LS575T
LG 42LS575TZD
LG 42LS575TZDBEKDLJG
LG 42LS575TZDBEKWLJG