You need a video isolator.

General Asylum

General audio topics that don't fit into specific categories.

In Reply to: Re: Start by identifying the source of the problem. posted by saywhat on February 20, 2006 at 18:23:34:

Your problem is common, and there are several transformers available to fix it. The basic problem is the same, but the cause is a ground loop between the safety earth connection of your AC power circuit and the safety earth connection of your cable TV installation. The cable is typically grounded where it comes into the house, and this is a different spot on your property than the place where your AC power is grounded. That difference in location leads to the offset voltage that causes the hum.
The fix is a transformer that couples the TV signal but isolates the ground. You should use one of these and remove any audio transformer isolators from your audio system.
The cheapest I've seen is the $10 Dayton video isolator. This should work well if you have typical cable TV.
One that includes a surge-suppressor and that appears to be slightly higher quality goes for $40 here:
http://www.elect-spec.com/video.htm
There are better ones out there. Jensen has just come out with some new ones:
http://www.jensen-transformers.com/

Dayton Video isolator from Parts Express (Open in New Window)

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Follow Ups Full Thread

Topic - Ground Loop Hum solution - saywhat 20:25:48 02/19/06 (9)

Use one outlet - benhen 13:01:24 02/21/06 (0)

Start by identifying the source of the problem. - Al Sekela 14:30:31 02/20/06 (4)

I used this technique recently, but still,.. - Bambi B 18:31:11 02/20/06 (1)

The problems are likely within the Yamaha and computer, - Al Sekela 11:32:37 02/21/06 (0)

Re: Start by identifying the source of the problem. - saywhat 18:23:34 02/20/06 (1)

You need a video isolator. - Al Sekela 11:27:07 02/21/06 (0)

These under $10/unit isolation transformers... - Hepcat 09:14:32 02/20/06 (0)

Re: Ground Loop Hum solution - SWG 08:41:33 02/20/06 (0)

Re: Ground Loop Hum solution - blackwax@mac.com 21:03:17 02/19/06 (0)

Follow Ups

You need a video isolator. - Al Sekela 11:27:07 02/21/06 (0)

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