TV-OUT Feedback/Buzzing?

[trunk8]

I'm building my own PVR box, and I ran into a bit of a snag last night. When I plug the TV-OUT on my Leadtek GeForce 4400 128mb into my TV, I get a pretty loud buzzing noise through the TV. It happens on any input as long as the computer has power and is plugged into my TV, using either S-VIDEO or Composite. It's definitely something that I can't ignore, I need to find a way to eliminate the noise. Looking for any suggestions, I'm hoping it's not the card because I can plug my laptop TV-OUT into my TV and I don't get any noise at all (or it's nearly inaudible). Thanks in advance for any help!

[gjunky]

I am guessing the buzzing is coming from your audio connection, not the video. Try and disconnect the audio and see if it goes away. If that is the case, you could try an optical audio out from the PC to the receiver (if that is your setup).

Just a thought.

-gjunky

[DonK]

Sounds like you have a ground loop. That happens sometimes, you might want to make sure your connections are good and grounded.

A ferrite core around the video cable may or may not help.

[MarkTO]

The ground loop is usually caused by the cable from your cable company having a different ground then the electrical system. As a test try to remove the cable signal from your TV and see if the buzzing stops (this includes the cable from any devices hooked up to the TV such as set top boxes and VCR's).

There are devices available to break a ground loop and stop the buzzing. This company ( http://www.jensen-transformers.com/ ) has a wide range of them but they are pricey. You may be able to find cheaper versions of these things at custom car audio shops or radio shack. These devices are also sometimes called baluns.

If it is your cable signal causing the problem you could try grounding it. Using a wire connect the outside of the connector or cable splitter cover to a water pipe. I am not an electrician so I am not sure if this is the best way to do this or if this may cause problems for the cable company.

I hope you can get this sorted out. I had the same problem and solved it by using an ISO-MAX isolation transformer on the audio line.

One more thing. Grounding can cause problems on video as well. If you see wavy lines moving around on your TV this is also a grounding problem.

Best of luck,
Mark

[trunk8]

Thanks for the suggestions everyone. That is correct, I do not yet have any audio cables hooked from my tv to PC or vice versa. One thing that someone from my work suggested was for me to try plugging the computer into another wall socket, because I do have the PC, TV, and my surround sound hooked into one wall socket. I'm not sure if this will take care of it, I haven't had time yet to try it. One other thing to note is that I haven't even brought the TV tuner into the mix yet, there is no coax involved at this point (other than what is connected to the TV which is connected to the PC). I merely have power, keyboard/house, network, and S-Video (or composite, both make the noise) plugged in at this point. What is the best way to make sure my connections are grounded? Also, Weezul mentioned a ferrite core, I've never really heard of that....Is that something that could be found at an electronics store like Radio Shack or something? Thanks again for everyone's help....I really don't want to have to scrap the project, I'll still use the PVR box but I would rather have it hooked into my TV.

[trunk8]

Great, thanks again. I really appreciate the help. I installed Beyond TV3 on my main PC and I love it, I can't wait to get this PVR box up and running.

[KrysX24]

MarkTO thanks for the awesome advice, I removed my coax cable from
the cable jack and the buzzing sound including the wavy lines went out.

I'll have to see what I can do to fix that perm. ground issue.

thanks again, great post.

Originally Posted by MarkTO

The ground loop is usually caused by the cable from your cable company having a different ground then the electrical system. As a test try to remove the cable signal from your TV and see if the buzzing stops (this includes the cable from any devices hooked up to the TV such as set top boxes and VCR's).

There are devices available to break a ground loop and stop the buzzing. This company ( http://www.jensen-transformers.com/ ) has a wide range of them but they are pricey. You may be able to find cheaper versions of these things at custom car audio shops or radio shack. These devices are also sometimes called baluns.

If it is your cable signal causing the problem you could try grounding it. Using a wire connect the outside of the connector or cable splitter cover to a water pipe. I am not an electrician so I am not sure if this is the best way to do this or if this may cause problems for the cable company.

I hope you can get this sorted out. I had the same problem and solved it by using an ISO-MAX isolation transformer on the audio line.

One more thing. Grounding can cause problems on video as well. If you see wavy lines moving around on your TV this is also a grounding problem.

Best of luck,
Mark