ground loop issue?

RyanJoz

I have a 60 hz. coming through the speakers. Any advice on where to start? it does get louder when turning up the volume on the receiver even with nothing playing. The receiver has no ground plug, just the polarized plug. I am very new to this so any help is needed. I have tried moving it to other rooms/circuits with the same results. Poor power into the house? Power conditioner? Bad I/C? All help is appreciated.

F1nut

Do you have a cable box hooked up with your system?

TNRabbit

If not, possibly a ground contact issue.

RyanJoz

Yes I have a Comcast HD (Motorola) box on the same system.

thsmith

disconnect the coax cables from STB and see if the hum goes away.

treitz3

1st, disconnect the cable box to see if it disappears. Then, check to see if the house is grounded properly [all points]. If that fails, try cutting off the circuit breaker of everything but what the stereo runs on. Does the hum still exist?

fbm211

Thats a common problem.You need to buy some sort of ground loop isolator I think.Call comcast and ask them if they can fix the problem first.

RyanJoz

Which of these is better/should I buy.

The one from Polk:
http://shop.polkaudio.com/

or the one from P.E.
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=180-075

treitz3

Have you even disconnected the box yet? Dang.

RyanJoz

Disconnecting the cable from the STB fixed it.

dpowell

There's your problem. I had the same thing with our local cable company. Had them out several times and we were able to trace the problem back out of my house and to their network. They never did fix the problem and I am no longer a customer of theirs. I have ATT U-Verse and no more hum. I never tried a ground loop isolator but it is worth a try. I was able to eliminate the hum from Cox by loosening the cable connection slightly and playing with it until I found a sweet spot where the hum did not occur but that is not an ideal fix.

BeefJerky

I recommend the ISO-MAX from the Polk Audio site. It is made by Jensen Transformers, and will just plain work. I tried cheaper brands and found that they would give me problems with digital cable and/or video on demand. The Jensen one completely eliminates the ground loop without affecting the signal in my experience. My ISO-MAX just uses standard nickel plated connectors, but according to the picture on Polk's website, this one uses gold plated connectors. Maybe they just changed the design?

headrott

Can a satellite box (coax cable) cause the same ground loop problem? I do not have cable, but do have directv hooked to the same (Equitech 1RQ) power conditioner. I know the equitech should take care of AC current ground loops, but apparently not satellite reciever box ground loops as it's just as loud as before installing the Equitech. It does lower the hum volume when I install a copper wire between the Equitech and the pre-amp. ANy help would be appreciated.

Greg

BeefJerky

It sounds like your satellite dish is not grounded properly. That is *very* bad since a proper grounding helps reduce damage in case of a nearby lightning strike. You need to have someone come out and fix that ASAP. Please do not wait to do this. It could also be due to the issue noted below, but is less likely with satellite.

I want to note that the problem with ground loops from cable lines aren't generally due to bad grounding. Rather, they're due to the fact that it simply uses a *different* ground point than the electrical lines. That's not really dangerous, just annoying. I believe newer building codes require the cable lines to be grounded at the same point as the electrical lines, which eliminates the problem. But, older residences are still plagued with this issue.

treitz3

headrott wrote: »

Can a satellite box (coax cable) cause the same ground loop problem?

Yes. I just disconnect it when listening but I believe that there is what you call an isolation transformer that is said to solve your issue. I have no first hand knowledge of one so don't hold me to it. Hopefully someone will chime in with what you need. You can always disconnect the cable coming from the wall when listening in the meantime.

Power conditioners [for me] have always yielded jack **** when it came to this and I'm properly grounded. :mad:

Ranger0912

Don't forget to check wall socket(s) for correct polarization. Can be a major contributor especially if your equipment uses different outlets. Believe me, I found out the hard way. Good luck.

RyanJoz

the IsoMax fixed my issue.

Huck344

Not to hijack this thread, but I'm having the same problems. Just recently moved to a new (old) house. Part of the house seems grounded, but the other part (where my equipment is set up) is not grounded. There are only two prong outlets in that room. I have a slight hum at all times (whether the DirecTV dish is connected or not). However, when I connect my PS3, the hum increases to an almost unbearable level. I purchased a cheap ground loop isolator from Radio Shack and it actually made it worse. I moved the sub to a different outlet on a different circuit and it got worse as well. I guess I have a few questions:
1.) If nothing is grounded, how exactly am I having a ground loop? I'm sorry, I'm not an electrician and don't quite understand how I would have a ground conflict with nothing grounded.
2.) Is it possible to install new outlets and run a ground wire to something in the crawl space below the house? Is this something I can do or should I call an electrician?

As I mentioned, I'm not very proficient in electrical, but it doesn't scare may. This can be a problem as I have shocked myself numerous times doing other stuff.

Thanks in advance.

Eric. . .

zingo

I would start by taking off the face plate of the outlets and seeing if either the box the outlet is housed in is metal, or if there is something else near by that is metal. If there is, sometimes you can use this to run a ground since you don't have best case scenario.

Huck344

zingo wrote: »

I would start by taking off the face plate of the outlets and seeing if either the box the outlet is housed in is metal, or if there is something else near by that is metal. If there is, sometimes you can use this to run a ground since you don't have best case scenario.

I'll have to check the box. But, you are saying that if it is a metal box (I assume it is because the house was built in 1948), I can just run a ground wire to the box and this will ground everything?

Amherst

zingo wrote: »

I would start by taking off the face plate of the outlets and seeing if either the box the outlet is housed in is metal, or if there is something else near by that is metal. If there is, sometimes you can use this to run a ground since you don't have best case scenario.

WRONG_WRONG_WRONG_ OMG :eek:

You should not be giving out advise concerning electrical power circuits-You DO NOT know what you are saying.

The poster would be doing due diligence by either hiring a competent electrician or befriending one that can help out. The fix is wrong and the symptoms are indicative of larger problems. This is not really going to be properly solved through conversation on a forum, in home testing is involved. Do not run ground to the outlet box.

Huck344

Amherst wrote: »

Do not run ground to the outlet box.

Is there a reason why? I know numerous outlet boxes that come with a ground plug, or I can install a grounding clip to the box.

Not being an electrician, can you please explain why this is a bad idea? Ideally, I would prefer if my entire house was grounded to a common pipe, but I don't really have the option to open up all my walls and run new cable.

Amherst

Huck, first off it's against NEC code. believe me when I tell you those codes were all written for good reason. I could go on and on about the reasons why it's wrong and fill this page, that would not be helpful.

Honestly though, you have described a home containing what is probably ancient knob and tube wiring that is in a failing state. I suspect you may have a possible failing neutral. Maybe? Maybe not? And therein lies the problem, you don't know until proper testing has been done. Do you have a possible fire hazard? Maybe,maybe not. If I were you I'd want to know by a test versus the alternative.

That is even if proper grounding has been performed on the existing circuit.

Huck344

Amherst - Thanks for the advice. The house is old. . . but not that old. Most of the house was remodeled about 15 years ago (long before I moved it). The panel and sub panel are relatively new (probably installed during the remodel). As mentioned in one of my previous posts. the majority of the house seems to have 3 prong grounded outlets. Just the living room and dining room seem to have the older two prong outlets. Now, I will say that I haven't removed the wall plates on the three prong outlets to make sure that they are all wired to a ground.

But, I do have to ask, if it is against NEC code, why do they sell outlet boxes with grounding plugs as well as grounding clips? I would think that if it was against code, they wouldn't manufacture and sell such products.

Amherst

First,the outlet (3 prong) does not indicate what type wire or circuit is necessarily "really" feeding a particular circuit.The fact that two prong exist and you are having problems warrants further investigation.

Two,the NEC is a rules committee, not a governing body. They don't specify what can be placed on a store shelf or not. There are quite a few electrical materials sold that because "old habits die hard", are still stocked. It doesn't make it right. You may be surprised to find out what is sold to the public that either has been phased out or never really had approval.The clips you refer to also have an industrial application that is still in use today. But not in a dwelling.

Good luck and hope this helps you.

Huck344

Thank you!

mgill

Brief side note - the ground loop isolator that is linked at Parts Express by RyanJoz is NOT compatible with DirecTV. Putting them inline will stop your signal from getting to your directv box. I have four of those puppies gathering dust because of this.

engrpas

I had the same problem and have a thread - look for my username. My solution is cheap and does not involve filters that can attenuate the signal. Here is what I wrote in my last post:

"Here is my solution - not the most elegant, not probably to code, but it works ...
I spent a day following all the grounding from the cable box outside the house to all the rooms with cable outlets - could not find anything wrong. I didn't want to use a filter as that would most likely attenuate the signal.

So I just ran an insulated #14 wire from an outlet ground to a coax cable terminal by adding a nut under the cable termination to secure the wire. The hum is gone, essentially the ground loop goes down that wire instead of the amplifier."