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Brijaws
01-27-2005, 09:37 PM
Any sugjestions on how to trouble shot Ground Loops and Hums? Can you meter these things?

mr2channel
01-27-2005, 10:51 PM
Brijaws I just posted on your coaxial ground hum issues, but for this one it may be as simple as not having equipment that is connected together via RCA connections on the same phase at the electrical panel. If you have a TV in one room and the gear is in another room, and they are connected by RCA cables, and they are on different phases at the eletrical panel, then they will complete the 60Hz cycle, thus hear the hum. if that does not fix the problem, try my standby, a kit that is ALWAYS in my van.....www.jensentransformers.com .

mr2channel
01-27-2005, 10:58 PM
cart before the horse, I guess I did not answer your question first. I would disconnect everything and start hooking everything back up one at a time, testing after each connection to see if the hum shows up, when it does, then you have found the guilty component, at that point disconnect the presumed guilty component, and continue to hook up the rest of the gear, testing each piece one at a time to see if you have any other guilty components, once you have identfied all guilty components, then you have the fun part of finding out why they are guilty of this dreaded hum. Devices that are connected to service providers are usually the guilty party, and when all else fails, I have chassis grounded guilty devices to cold water pipes under the house and gotten rid of hums in the past. good luck ground loops are always fun. If you get stuck call Bill Whitlock @ jensen trasformers, he is a really great guy and has helped me out in the past with a few real buggers.

AudibleSolutions
01-28-2005, 12:19 AM
Very good informatioin 2channel . Measure shield to ground. Same way you would measure in high voltage: Neutral to ground. You want no voltage in either case.

Alan

LarryFine
01-28-2005, 01:16 AM
Being lazy, I might just start by disconnecting one thing at a time, check the results, reconnect it, and try another. (I'd dread just unplugging everything, especially if I didn't do the original hook-up.) To me, it's as important to pinpoint the problem and solution as it is to accomplish it.

Troubleshooting is mostly a process of elimination, but there's a lot to be said for experience and intuition; add a systematic and efficient approach, and you can save a lot of time and reduce repetitive motions. As I said, I'm lazy; I believe in "economy of motion."

Okay, enough preaching! :roll: Start with the most common causes; cable coax shield, powered subwoofer power cord ground, etc., then on to checking out the aforementioned power source(s) for physical loops, such as multiple circuits and multiple room interconnections.



Edit: how did this response get posted at 5:16 pm on Friday, the 28th?

ejfiii
01-31-2005, 07:13 AM
but here is a link I have in my sig at AVS to a thread about ground loops. Seems like this subject comes up at least once a day there and no one knows how to search. Lots of good info there:

click here (http://www.avsforum.com/avs-vb/showthread.php?s=&threadid=322698)

jwalkup
01-31-2005, 08:43 PM
.
Edit: how did this response get posted at 5:16 pm on Friday, the 28th?

Sounds like you need to change your time zone in your profile to GMT-05:00.
Then you can edit your edit.

LarryFine
02-01-2005, 07:36 AM
.
Edit: how did this response get posted at 5:16 pm on Friday, the 28th?Sounds like you need to change your time zone in your profile to GMT-05:00.Done, thanx!

Anonymous
09-13-2005, 08:21 AM
:? what are the possible causes for increased voltage between earth and neutral
:? what could be the % of current passed through the neutral when the loads are 120, 125 & 130 in R,Y,B phases resply.

kplummer
09-13-2005, 10:23 PM
Being lazy, I might just start by disconnecting one thing at a time, check the results, reconnect it, and try another. (I'd dread just unplugging everything, especially if I didn't do the original hook-up.) To me, it's as important to pinpoint the problem and solution as it is to accomplish it.

The problem with this method is that ground hums/loops are not always induced by one device, in fact sometimes they arent even caused by one device alone. I had a system once that the sat reciever and the digital cable combined were the issue. If just one of the two were in the system it was ok, but if they both were then there was the hum...

krasmuzik
09-14-2005, 03:56 PM
There is a great sticky thread on troubleshooting audio hum over on AVS in the audio theory and setup forum. Another great resource is the Jensen sponsored class at CEDIA - maybe they will make their white paper available (it is huge!)

I just mostly solved a recent hum/hash video problem with a Monster power strip with the coax RF in/outs. Customer had OTA/Cable/Sat/Security feeds and some others I had no clue on - had to break them all to make it mostly go away.