[xluben]

Tonight I unhooked my Marantz reciever and thoroughly cleaned it (inside and out). I hooked it back up and now there is a noticeable hum from my subwoofer when nothing is connected to the AUX input (but the cable is inserted).

Let me explain the circumstances in more detail.

No hum ("or" goes in between each item):

Reciever off
Subwoofer off
No cables plugged into AUX inputs (but sub plugged in)
Subwoofer not plugged into reciever
Input selector on anything but AUX (AUX and subwoofer connected)
Cable plugged into AUX is plugged into source (iPod, Laptop)

Hum occors:

When everything is on, sub is connected to reciever's Pre Out, reciever's selected input is AUX, and cable is plugged into AUX (but nothing is plugged into the other end of the cable>

Hopefully this is clear. Basically I have an iPod dock connected to my reciever's AUX inputs with a mini-to-RCA cable. When everything is plugged in and turned on (music paused) there is no hum. As soon as I pull the iPod out of the dock, there is a loud hum out of the subwoofer. The hum's loudness varies with the reciever's volume control.

The strange part is that none of this happened before today. I have tried everything I can think of to get the hum to go away, but nothing will work. Is this something internally between the Pre Out and AUX in signals? Or is it a grounding issue?

The reciever has a post on the back called "Chassis Ground" Do I need to hook this up to something? (I put 16ga wire in it and touched it to a screw on a light switch, and I thought this stopped the hum, but now it no longer seems to work ).

Also, I have tried other inputs.  The PHONO input makes the hum MUCH louder.  The other two inputs have the same amount of hum as AUX.

[avahifi]

Do you have a 3 pin AC power cord on anything in the system?  If so try a "cheater plug" on that so that the third pin ground connection is open.  Often this is a source of hum caused by a ground loop,

Frank Van Alstine

[xluben]

Nope, nothing in my system has a ground pin on the outlet plug.  I thought maybe the lack of this could be causing the hum.

[Levi]

It sounds like a grounding problem.

Have you tried switching into different cables?

Also when you switch into a different source like tape or CD do you still hear the hum?  

Let's back track.  The hum was not there prior to cleaning.
Is it possible that you have touched something inside the unit when you cleaned it up?  

Tonight I unhooked my Marantz reciever and thoroughly cleaned it (inside and out). I hooked it back up and now there is a noticeable hum from my subwoofer when nothing is connected to the AUX input (but the cable is inserted).

Let me explain the circumstances in more detail.

No hum ("or" goes in between each item):

Reciever off
Subwoofer off
No cables plugged into AUX inputs (but sub plugged in)
Subwoofer not plugged into reciever
Input selector on anything but AUX (AUX and subwoofer connected) ...

[xluben]

Different RCA cables (interconnects)?

No, but I'll have to give it a try.

The only source that causes the subwoofer to hum is the AUX.

I was thinking that I could have done something while cleaning, so I opened it back up, but couldn't find anything obvious to fix the problem.