Humming noise through speakers

[stompe]

I have connected my tv up to my computer by using a 15 pin monitor lead (10m) and a 3.5 stereo jack 10m cable but I am getting a loud humming noise through my tv speakers. Can anyone help me resolve this problem or suggest a solution please?

[ChuckFickens]

have you got the audio lead running close to power leads at all? if it's a cheap badly screened audio lead then it will pick up hum from that. so moving it away from the power leads will help.

Also play with the volume on your computer and TV, turn the computer volume up more and your TV volume down

if you still get a hum you probably just need to buy a better quality lead that is better screened

[stompe]

These are the leads I bought from Maplins.

http://www.maplin.co.uk/module.aspx?moduleno=9 7367#features

http://www.maplin.co.uk/module.aspx?moduleno=4 2530

Thanks for your advice.

[ChuckFickens]

the audio lead looks ok, turn the computer volume right up as high as possible and the TV down.

[beso]

Does the television or any of the other devices connected to it have an earthing pin on the power plug? And the computer and TV plugged into different power outlets?

If so you probably have a ground loop. The house wiring and the ground braiding of the audio cable form a loop that picks up the electromagnetic field of the mains power.

The current running in the ground loop causes a voltage drop in the audio shield which produces a difference between the ground levels of the computer and TV causing a hum on the audio.

You can get a ground loop isolator for the audio connection.

Otherwise it can help a lot if you plug the tTVand computer into the same power point and run the mains lead close to the audio cable. The area of the ground loop circuit should be minimised.

[stompe]

Thank you very much Beso. I have bought a ground loop isolator and it has cured the problem. You have saved me any more trips to maplins, I was beginning to think this problem was unsolvable.