Bizarre buzzing sound through DVD player ... any ideas? (1 Viewer)

[TedE]

I was trying to help a friend out with a problem with a very annoying, loud buzzing sound that she gets with her DVD player. Here's her (decidedly low-tech) set-up:

Toshiba SD2900 hooked up via composite cables through a modulator into the coaxial cable input on her TV (old TV with no composite inputs).

My first reaction was "Buy a new cheap TV with real inputs!", but she really only uses this occasionally for movies and doesn't care to spend the less than $200 to get a new set.

The buzzing sounds like interference; it is cyclical. Buzzes for about 5 seconds, then fades away for 3-4 seconds, then comes back. I played around with moving her player away from all the other components (TV and bookshelf stereo). No effect. The interference is definitely coming through the video cable though: unplugging both the L and R composite audio cables has no effect.

Could it be interference through the actual wiring in her building? I didn't have the chance to move every thing around that much to check it. Aside from buying a new set with composite (or at least S-Video these days), is there anything else I can check to determine if it is related to the modulator or something else?

BTW, it is definitely from the DVD player source since her VCR runs through the modulator and has no issues. I should mention that she does not notice this buzzing from all DVDs, or at least there are some disks that seem to not have this problem. Possibly related to disks that are encoded for surround? Then again, completely unplugging the L and R audio from he modulator does not make the buzzing go away. Sorry for rambling. Any ideas?!?

Thanks!

 

[Chu Gai]

does it go away if you disconnect the cable from the TV?

 

[TedE]

Well, yes, when the coax is unplugged from the TV the buzzing stops; as I said in my post it's from the DVD source. I seems to be the video cable that is causing the problem (unplugging the video cable from the modulator stops the buzzing; unplugging the audio cables has no effect).

 

[Chu Gai]

Just wanted to make sure it was clear in my mind. This is possibly a result of a ground-loop and may likely come from an improper cable install where the shield hasn't been grounded outside. A couple of choices....

call them up and inform them of the problem and see if they'll come out to rectify it

take care of it yourself

purchase a ground loop eliminator appropriate for the frequencies that're being passed by your cable. sources for that could be radio shack, Mondial (sp?), and Jensen Transformers.

Some people have reported that plugging all the equipment, and that includes the cable, into a surge protector has taken care of their problems. So if you have one of those around you can try that first. If you don't, a fairly inexpensive one is one from Stratitec.com which you can buy online for around $25 at directron.com or if you've got a Sam's Club, they sell it bundled with a smaller surge protector for under $20.

 

[TedE]

Could be ground loop ... but she doesn't have cable. I'll have to take a closer look at her set-up. Coax is going from VCR to modulator, composite from DVD to modulator, coax out from modulator to TV.

Funny thing is it only buzzes on certain DVDs, like DVD X will always buzz, DVD Y never does. Could it be something to do with encoding? Kinda bizarre.