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Please help I have a strange grounding problem

I recently bought a FIM 880 outlet and installed it myself. I plugged in my amp and cdp but I'm getting a fairly loud "humming" when I play my tuner only. I don't have dedicated outlets( I'm in the process of making this my next project)so I have my tuner plugged into a Monster Cable 2000 outlet which is in another outlet on the same wall.Both outlets are on the same line as when I shut off the breaker there is no power on this wall. The strange thing is when I unplug the cdp, the hum goes away completely.It only comes back when I plug the cdp back into the same outlet as my amp. Another weird thing is when the hum is there and I get closer to my amp, the hum increases in volume as if my body is acting as an antenna. I'm not a technical guy,but it appears to me that there is some kind of a loop and by unplugging the cdp the loop is taken out. I would surely like some advice on this new and strange situation. Thanks for your help and advice.
sherod
alexanderj
139 posts
 
Did this problem start with the changeover to the FIM 880?

Is the 880 an isolated ground style recepticle? FIM's website won't come up for me to check. If it is and it is mounted in a conduit type installation you may have NO GROUND connection to the "U" terminal. You may want to purchase an inexpensive (typically under $5.00) outlet tester (has 3 neon lites) and verify that the outlet has a ground as is wired with correct polarity.
stehno
1,453 posts
 
Since you installed the FIM 880 yourself, you can float the ground yourself by simply tripping the circuit, disconnect the ground from the FIM outlet, and then test.

Also, make certain that the house wiring to the FIM outlet are connected properly i.e. hot to brass or darker screws and neutral to the silver colored screws.

-IMO
j_k
234 posts
 
Don't float grounds except to troubleshoot - never a good solution. With a bit of rigor, one can find the solution... When I had an issue, it took me 20+ hours to figure this out - and I am capable of performing Electrician duties... One thing to try - if you have cable, sat. or antenna, disconnect any of these connections to see if the hum goes away.. You may have a ground loop thru a antenna / cable connection.
sherod OP
1,690 posts
 
Thanks everyone for your great suggestions. I will consider them all. Again, much appreciated. P.S. I'm not so sure now that this is a true ground hum problem after all. I usually listen only to a local college FM station that plays mainly jazz and classical.After trying without success the cheater plug on all components, I tried some other FM stations and the hum wasn't there. I then went back to my regular station and the hum was only there, so I thought maybe it's with the radio station.The strange thing is the hum decreases and increases in volume as I move toward and away from my amp. Then, while fiddling with my tuner( modified 1980's Sansui T-80 analog)I pushed the stereo button to mono and the hum disappeared completely. Then when pushing the button off and on repeatedly, the hum would come and go as well( mono=no hum,stereo=hum ). It was nice to finally eliminate the hum, but listening to mono is not my cup of tea. Any further suggestions ?
gabbro
88 posts
 
What is your antenna situation? If you improve the reception, it may solve your problem. A good attic or roof-mount directional antenna with a rotor is always a good idea.
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