grounding problem?

[xchangx]

My subwoofer (connected to my reciever) gets a grounding hum like every other hour. I opened the reciever and all the wires were connected and none were loose, does anyone know what it is? If I turn the subwoofer off, everything's fine, which means it's only going through the subwoofer. If I tap (or bang) on the reciever it goes away, making me believe it's a grounding problem.

Thanks,
Chang

 

[ScottMac]

If it's a two-prong plug, reverse it (rotate it 180 degrees). If it's a three-prong power plug, check the grounding on the outlet.

Good chance it's just a flakey shield on the audio cable from the amp to the SW.

FWIW

Scott

 

[Evadman]

It may be feedback from the dc/ac converter as well. Frankly, it totaly sounds like a connection issue. Is the PCB fully grounded to the chassis with screws? Most PCB's require grounding at every mounting point so the ground trace does not get overloaded.
I saw your original post in Tech suport, that really is where this post belongs

 

[TurboMan]

Are the receiver and sub plugged into the same outlet? If not check both to make sure both outlets are wired correctly. I'd say about 33% of the outlets I've replaced for customers are wired incorrectly (backwards). The neutral (white) wire needs to be connected to the side with the big slit on the plug side.

 

[Jerboy]

<< Are the receiver and sub plugged into the same outlet? If not check both to make sure both outlets are wired correctly. I'd say about 33% of the outlets I've replaced for customers are wired incorrectly (backwards). The neutral (white) wire needs to be connected to the side with the big slit on the plug side. >>




You maybe having a ground loop in your grounding circuit in the wall. Do you see many pros cutting off their third prong off? I do. It's the easiest way to escape ground loop. Instead of cutting off, I'd use a three prong to two prong adapter though.

 

[TurboMan]

<< You maybe having a ground loop in your grounding circuit in the wall >>


That's exactly what I was getting at. However, you should never cut off the 3rd prong - unless you have a death wish. It is there to shunt current back to the panel in case of a short. You usually only see 3 prong outlets on things that have a metal case. I mention the ground loop because that's what my parents house had. When I hooked up their DSS system a ground loop popped up. The computer (server) was connecter to one of the receivers in a room on a different circuit. The outlet the receiver was hooked up to was wired backwards. System kept locking up. Corrected the wiring on that outlet and all is well. I would definetly check the outlets.