lcd tv mains buzz

patrickolee

Hi,

Recently bought a panasonic tv from peats, 32" LCD. Haven't got the exact model here at the moment. I noticed a mains buzz sound coming from the tv, so I returned to peats with it. We powered it on in the shop and no longer could hear the sound. Anyway they replaced the TV just to be sure (fair juice to them). Got the new TV back and found it has the same buzz coming from it. Only comes after been switched on for about 1/2 an hour. My partner can't hear it, but I can when the volume is switched down or there is a quiet period in the program I'm watching. Wrecks my head! Did a quick bit of googling and came up with this

http://www.avforums.com/forums/archive/index.php/t-289319.html

and a possible solution of

http://www.psaudio.com/products/humbusterac.asp

Unfortunately though the humbuster is an american product. Does anyone know of an Irish/UK equivalent, or indeed if there is anyway to remove the buzz?

thanks

Homer

It would help a great deal to know what you have the tv connected to? DVD/Sky/NTL? Does it only happen while watching TV or on DVD too etc etc. It does sound like a ground loop issue but this normally manifests itself as rolling lines on the screen but could still be the source of your problem.
A ground loop occurs when some devices in a system are not connected to the same electrical ground as the other devices. This can create a voltage potential different between "ground" on the pieces of equipment.
Need more info to better solve your problem!
Hope this bit helps.
And yes there are devices available in Ieland to resolve this if it is a ground loop problem.

patrickolee

Actually thought it might be one of the other devices alright, so I disconnected everything including NTL and switched the sound to mute. Still hear the buzz. About the rolling lines, I do get that on channel 4/E4, to a slight extent, but not so bad. No other channel has though and dont see that problem when watching DVDs, so I was putting that down to bad reception.

Homer

Hmmmm. If you have disconnected EVERYTHING that was connected to the TV and powered it up, then switched it to mute, and the problem is still there then there is either a problem with the set (unlikely if you have swapped it) or there is a power issue. Try getting a power conditioner (harvey norman or peats)
This might explain a bit better about "dirty power" although it is uncommon in new houses in this country.

http://www.monstercable.com/productdisplay.asp?pin=1033

Kind of trial and error unfortunately but with a bit of perseverance you'll get it sorted!

patrickolee

Thanks for the replies industria.

It's an old house, but I recently got it re-wired. Reckon it must be mains, or else I was very unlucky and got two dodgey tvs! Thinking of taking a trip down to maplin and getting one of these

http://www.maplin.co.uk/module.aspx?ModuleNo=46830&doy=15m8

6-Way Mains Conditioner and RFI Filter for Home Cinema & Hifi

Not too expensive anyway, probably worth a lash.

cheers, I'll post back if it works, or not.

patrickolee

Nope, didn't work. Must be just the TV make, or else I'm too particular! Shoulda bought a Sony :-(

conax

I have come across this problem many times in the past, however I have also found different solutions in each case, funny enough most of the problems occured afer there was electrical work carried out on the premisis. I have one question. Is the TV and the source equipment plugged into the same electrical outlet?

patrickolee

No. I plug everything out, just the tv is plugged in, no other components and sound switched off. I have noticed that the buzz does not start when power is applied to the tv, but starts as soon as an image (even snow) is shown on the screen.

conax

Hmmmm, should have read the full thread was going along the lines of "industria" the ground loop or induction due to loading.Have you tried the set in another socket, or checked the voltage to see of its close to 230V, other that that I am at a loss. If you get it sorted I would love to know your solution.

Jip

I have an LCD back from repair for the second time due to this problem, first time round the power supply in it was replaced which seemed to work fine for a while but after a week or two it returned. It's now away waiting for more parts so I'll see how that goes whenever I get it back.