Dreaded ground loop hum

polk500

Thanks in advance.

So for whatever reason my system started to hum last week and it's related to the cable company.

Because when I remove the cable from the DVR the humming stops. Cable guy came in and couldn't fix the issue.

So I used a cheater plug on the Parasound Amp as that's the component that when used with the cheater plug (read about it here on the forum) humming goes away. Cable guy states that this is wrong and could lead to other problems because without a ground the breaker (20 amp) can't trip. done some research seems like he is right.

One solution is to use a GFCI the other is to use a TV cable ground isolater.

So of course I'm going to you folks for thoughts and perhaps other possible solutions.

Cheers Roger

Msabot1

Those CATV installers are notorious for incorrect grounding if at all! Hum goes away when disconnected should tell you something! Heck most of em do not know how to cut a proper fitting anyway. Check the transition point from the outside to point of entry for a correct ground.

polk500

Msabot1 wrote: »

Those CATV installers are notorious for incorrect grounding if at all! Hum goes away when disconnected should tell you something! Heck most of em do not know how to cut a proper fitting anyway. Check the transition point from the outside to point of entry for a correct ground.

I checked that already seems to be solid and it is grounded to the main house ground.

What I'm thinking is it's further down the line as it worked fine and just started for no reason. So I suspect they were working at a junction station down the road and messed up at that point.

So now I left with trying to fix it without putting my equipment at risk of getting fried.

[Deleted User]

Hello,
You're going to need a good quality ground loop isolator to go between the cable connection and your DVR. I would suggest contacting the Jensen Transformer company at: http://www.jensen-transformers.com/ they'll need to recommend one that has sufficient bandwidth for your equipment.
Regards, Ken

tonyb

Dude, I've been using cheater plugs for over 8 years on one component or another. Never a problem, and believe me, the breaker still flips off on it's own when crap happens.

dpowell

I have a great ground loop isolator that I used when I had cable. Now that I have satellite, I no longer need it. PM if you are interested in working something out.

CoolJazz

In the typical consumer unbalanced system, ONE ground should be present. Any more than one ground lets currents flow that can effect the audio. Lifting grounds on other than the one, can be effective.

But one ground should be present for safety. Shock hazard can be present if there is no ground and it not be a current flow high enough to pull a breaker. A chassis having voltage present where there is no ground has no path to pull the breaker. At least until you complete the circuit! (Insert that pic of the floaters on the pool here...)

CJ

polk500

Thanks for the replies folks, I'm going to check out a isolator and see if it works. Until then I've installed a GFCI to plug the cheater plug into.

Nothing will probably happen but $20:00 is cheap insurance.

Cheers Roger

polk500

Update on this thread, received and installed the Jensen Isolator today THE HUM IS GONE!!!!

Thanks for the advise folks and thanks dpowell for the quick shipping.

Cheers
Roger

[Deleted User]

I'm glad you got the Jensen, it has sufficient bandwidth to not adversely effect your video response.