Earthing issue between TV and Amp?

Posted by: garyi on 12 October 2007

I have just got a new LG tv. As soon as it is plugged in the transformer in my naim 200 starts making very odd noises, it sounds like its cycling with the tele. If the TV is brighter the louder it gets, the darker the picture the more quiet.

Its quite prominent.

Any ideas what I can do (Installing separate spurs is not an option)

Posted on: 12 October 2007 by JonR

gazzer, have you got your TV plugged into the same wall-socket as your hifi?

As you know I've got a 200 as well and my (main) hifi system has always been in the same room as my TV (a 3 year-old Philips 30" LCD) yet I have never heard a peep from the amp's transformer - and I often listen to the system with the TV on.

My TV is plugged into a completely different wall socket to the hifi (albeit they are all on the same ring main) hence my question.

Posted on: 12 October 2007 by AV@naim

also...

what are the earthing arrangements on your Tv, I assume the Tv is not mains earthed, but is the
aerial downlead?

whats the system setup?

Posted on: 13 October 2007 by David Dever

A power conditioner for the TV is also a good idea.

Posted on: 13 October 2007 by garyi

Am pretty sure its a switch mode powersupply in the TV causing the issues.

That being said I have moved the mini and harddrives out the room and its better.

Posted on: 15 October 2007 by IlanT

Hi garyi,

It has been my experience, that some video products as well as practically all cable content suppliers EARTH their signal ground. In such a case, and in a typical Naim setup, where signal ground is also EARTHED (through sources), a ground loop is created, resulting in audible hum and sometimes visible interference lines (on screen).
There is a simple and inexpensive solution in the form of a device called "Ground Isolator" or "Ground Block" - a cylinder of some 8-10cm in length, 2-3 cm in diameter, connected between
an EARTH carrying video cable to its destination.
In Israel the device intallation is done FOC by cable content suppliers on request, when it is connected at the entrance to the house, therefore serving all connected equipment.
It is also available on the market for ~10 pounds.