Cable ground loop

[pyroponic]

Hey guys, I get the infamous humming noise (RSP-1068 + RMB-1095) whenever I have the cable TV plugged in, and it's really annoying to have to discconect them anytime I want to watch a DVD or play music. I believe I saw a while back about an isolator for like $50 that eliminates the problem? I've been meaning to fix this so if anyone could provide the link or information i'd appreciate it.

[Kevin D]

Got a Jensen ISOMAX VRD-1FF on mine. Works wonders!

http://www.jensen-transformers.com/iso_vid.html

It's $60+ shipping from them. You might be able to find it cheaper online somewhere else.

Kevin D.

[janmike]

Have the Cable company ensure that the coax is grounded. I did and it never cost me a cent. Hum gone.

[peterS]

Have the Cable company ensure that the coax is grounded. I did and it never cost me a cent. Hum gone.

getting a cable company to do much of anything can be a little more difficult in the us ops:

partsexpress sells an inline isolator

[Sim reality]

I've always wondered... If you grounded the outer coax jacket to the same ground as the equipment, shouldn't that get rid of the hum?

[Kevin D]

I've always wondered... If you grounded the outer coax jacket to the same ground as the equipment, shouldn't that get rid of the hum?

That's what you're doing when you screw it in. You're actually introducing the hum to the ground of the system. The correct way is to ground it to true ground as it enters the house. Unfortunately, depending upon how bad it is, this doesn't always fix the problem.

Kevin D.

[wkhanna]

So is the idea to get the potential between all components equal?
Or eliminate all potential entirely?

[Kevin D]

You got it. Power always follows the path of least resistance. This is usually through your inter-connects and out as noise in the system. With all potential equal, it will travel out the ground where it should. Otherwise you need to eliminate the path through isolation transformers or none conductive means (optical cables, etc).

Kevin D.

[wkhanna]

Hey, even I have my moments!!!!

Thanks Kevin.

[wkhanna]

OK. Now I’m on a roll.

Do YOU ground all components together as and SOP, or only as an remedy for noise?

On a side note, I just ran a cheap Toslink from my CDp this weekend, and noticed improved SQ on redbook. It is probably more an indication of the low quality of my current Coax though.

But I have always wondered why they don’t use optic for all digital x-fer due to it’s immunity to varying potential, RF and EMI/EMF between components.

[Kevin D]

Optical adds in the variance of glass quality. It's a heated debate, but generally you can get better QA from a coaxial cable.

As for me? Fixing inherent electrical problems has cured me of all my problems, aside from needing the cable isolator. I added a dedicated 30amp circuit for my equipment and started getting interference on my TV (which was now on a different circuit). Turns out there was some issues in the electrical panel. The panel was grounded, but not the ground lead coming in from the street. Also instead of grounds on one side / neutrals on the other, the panel had a random approach to it. Grouping these together helped out as well.

The cable thing was just easier to solve with a patch.. If cable was attached to ANYTHING tied into the system, I'd get a buzz. It could be cable to the TV. Cable to the VCR (only connected to the 1098). Even cable to the bedroom TV, which has a video wire from zone 2 on the 1098!

Dealing with big houses and huge multi-source, multi-room systems, isolators are usually the only answer. Imagine having a 16x16 AV switcher with TV's and sources all over the house. You've got grounds from different circuits, different panels, and sometimes even different service feeds!

Crazy stuff.

Kevin D.

[Club1820]

Hope you dont mind - I am resurrecting an old thread.

I am having the same ground loop Cable TV problem with my 1068.

Chanlon, did you ever get your problem solved?

Has anyone used any other Isolation Transformer other than Jensen's? $60 for me right now seems kinda steep.

How about this one from Parts Express? Anyone have any experience with this one? DAYTON VIT-1 VIDEO ISOLATION TRANSFORMER http://www.partsexpress.com/pe/showd...number=180-075

Any others available that work?

Finally, I did hook up my cable line to my Rotel RLC-1040 line conditioner. It did eliminate the hum but the picture seems degraded a bit. I would then rather not do this and get an isolation transformer.

Suggestions anyone?

Thanks in advance.

[Kevin D]

If you want a cheap fix, I believe two 300ohm to 75ohm adapters ran together also work.

It's those coax to two wire adapters used to convert antennas or older tv sets to coax. Splice the wire ends inline with each other and you should have an adapter with female coax ends. Connect this inline with your cable and you should be set.

Kevin D.

[Club1820]

Thanks for the reply Kevin. I did see where you posted that solution on another thread in the past regarding this same issue.

I believe I have a couple of those laying around that I actually used for their original purpose way back when VCRs and Cable first came out. I will give it a go.

Any others try the Dayton solution from Parts Express?

Thanks again!

[Club1820]

Kevin, one more question. How was the picture once you installed the Jensen Transformer? did it degrade at all?

Thanks.

[Kevin D]

Heh.. None that I noticed. Of course it can't get much worse around here.

Kevin D.