How does one fix Schizophrenic, intermittent ground loop?

caesar · Jul 24, 2016

Was hanging out at a buddy’s house this weekend - watching sports on TV and listening to music from the same system.

Unfortunately, his system has a very interesting occurrence with what seems like an unpredictable, intermittent ground loop. His right channel occasionally starts buzzing when playing music - but then it goes away – on its own, without touching or unplugging anything.

Furthermore, despite an annoying high pitched sound while playing music, his crazy system sounds just fine when the preamp is flipped to tv. So we were watching sports and it was all cool. … Then flip the switch on the preamp to the 2 channel audio system, and the right channel buzzes. Flip back to TV and no buzz!!!??? Does anyone understand why that is?

His cables are all messy, and all is plugged into 3 dedicated lines. We were hanging out and chatting, and did not try to plug and unplug.

We went to lunch for a couple of hours, and the buzz on the 2 channel system went away. But he let me know that late at night it came back again. Does anyone understand what is happening?

treitz3 · Jul 24, 2016

Hello, Caesar. Could it be caused from something like a fridge, freezer, fan (or old SS dimmer attached to said fan), fluorescent light fixture, sump pump or HVAC system that turns on intermittently? Also sounds like he may have an issue with his pre. Does he have one to swap out and check to see if this is the case?

Tom

caesar · Jul 24, 2016

treitz3 said:
Hello, Caesar. Could it be caused from something like a fridge, freezer, fan (or old SS dimmer attached to said fan), fluorescent light fixture, sump pump or HVAC system that turns on intermittently? Also sounds like he may have an issue with his pre. Does he have one to swap out and check to see if this is the case?

Tom

Thank you. I'll ping him. But are you suggesting that when a large appliance goes on, it causes that hum in his right channel? The strange thing is that same channel works just fine with the TV going, but wigs out when switching to 2-channel.

microstrip · Jul 24, 2016

caesar said:
Thank you. I'll ping him. But are you suggesting that when a large appliance goes on, it causes that hum in his right channel? The strange thing is that same channel works just fine with the TV going, but wigs out when switching to 2-channel.

Electrical appliances injecting some leakage current in the ground line can cause this effect. Does your friend own monoblock amplifiers?

caesar · Jul 24, 2016

microstrip said:
Electrical appliances injecting some leakage current in the ground line can cause this effect. Does your friend own monoblock amplifiers?

Yes, but I think both were plugged into the same line.

treitz3 · Jul 24, 2016

I would suggest first swapping out the pre before anything else. If this doesn't do the trick, then your friend may be looking at multiple issues.

Tom

caesar · Jul 24, 2016

treitz3 said:
I would suggest first swapping out the pre before anything else. If this doesn't do the trick, then your friend may be looking at multiple issues.

Tom

Thank you. By swapping out, do you mean getting another unit into the system, or plugging the current one into a different outlet?

treitz3 · Jul 24, 2016

Another known working unit into the system.

Tom

fas42 · Jul 24, 2016

I've had such things happen when a solid state part was on its way out - a complex chip with much internal circuitry had developed a poor connection, which, depending upon everything, would be fine, or start playing up. Isolating the part and giving a vigorous tap - the shock treatment - might help, or make things worse. The only real solution here is obviously to replace the part, if it can be identified and is available - as treitz3 suggests, first identify the faulty component.

amirm · Jul 24, 2016

Have him disconnect the pre-input to the cable box and see if it goes away.

RBFC · Jul 24, 2016

Also, have him swap left and right cables through the system to locate where the "buzz" switches channels. The cable tv input is another culprit, as Amir mentioned.

Lee

asiufy · Jul 25, 2016

amirm said:
Have him disconnect the pre-input to the cable box and see if it goes away.

+1 here. Cable boxes are a major source of noise, and to have them anywhere near the system is usually a problem. There are some "hum buster" gizmos that are supposed to solve the problem...

caesar · Jul 25, 2016

Gentlemen, thank you for the replies. I think what happened is that my friends wife came home and turned on the washing machine, which sits on the same side of the breaker box as his dedicated lines..... I'll also mention disconnecting cable.

Does anyone have a sense of why only the right channel was affected? Thank you again.

NorthStar · Jul 26, 2016

Is it a mono washing machine?

JackD201 · Jul 26, 2016

NorthStar said:
Is it a mono washing machine?

If it were it stands to reason it would have been the left channel then! LOL!

NorthStar · Jul 26, 2016

Beats me!

caesar · Jul 26, 2016

NorthStar said:
Is it a mono washing machine?

You are one creatively thinking dude!

stehno · Jul 27, 2016

caesar said:
Was hanging out at a buddy’s house this weekend - watching sports on TV and listening to music from the same system.

Unfortunately, his system has a very interesting occurrence with what seems like an unpredictable, intermittent ground loop. His right channel occasionally starts buzzing when playing music - but then it goes away – on its own, without touching or unplugging anything.

Furthermore, despite an annoying high pitched sound while playing music, his crazy system sounds just fine when the preamp is flipped to tv. So we were watching sports and it was all cool. … Then flip the switch on the preamp to the 2 channel audio system, and the right channel buzzes. Flip back to TV and no buzz!!!??? Does anyone understand why that is?

His cables are all messy, and all is plugged into 3 dedicated lines. We were hanging out and chatting, and did not try to plug and unplug.

We went to lunch for a couple of hours, and the buzz on the 2 channel system went away. But he let me know that late at night it came back again. Does anyone understand what is happening?

You mean after all these years people still ground their components?

There are several things to consider:

1. Lifting the ground.
2. Superior line conditioning.
3. Dedicated circuits at the service panel should all be on the same phase / leg.
4. Loose connections.
5. All wiring / cables should be kept separate (not touching) from other wires / cables.
6. Faulty component.

Any combination of the above could be the culprit.

How does one fix Schizophrenic, intermittent ground loop?

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