Do you have a cable box and subscription toreceive the pogrammes?
Is the TV tuner set up for the correct type of signal(part of the initial installaion menu) eg if you are in UKit should be set for PAL I otherwise you will get no sound.
PS3 and the DVD do not use the tuner so will always work.
Maybe this helps?
I have my Samsung Series 5 TV LCD. When i play PS3 on my TV it has a sounds or when i watch DVD's but when i start to turn it to TV and put the cable at the back of it, it has no sound but when i put the cable on the other TV it is good and has sound. I'm just wondering why does it happens i check all the audio options still nothing work. Just another question, it has also a bad video on screen and no sound when i put the cable on the back.