I have a Denon AVR-1602 receiver and a Velodyne CHT-120 subwoofer. Both haven't been used for a few years but were recently brought out of storage and hooked up.
The first thing I noticed was a buzzing noise from the sub when hooked up to the receiver. I know this is a sure sign of not being grounded somewhere so I unplugged the cable TV coming into the house to test it and also plugged the sub into multiple different outlets to no avail. The other thing that puzzled me was: a) there was no buzz when the sub was powered on but not connected to the receiver and b) even when connected and with music playing there was no signal reaching the sub aside from the buzzing.
I have since seemingly determined that the problem is not with the sub by hooking it up to the receiver through the speaker level inputs and was able to produce no feedback signal.
I opened up the receiver and upon closer inspection it seems to me that the sub pre-out connector is broken. If you grab it from the outside (back panel) of the receiver and try to rotate it either way it actually spins both ways a little bit, which obviously isn't normal. From the inside there appear to be some jagged edges as if the connecter has broken up somewhow but it's very difficult to tell. I don't feel comfortable taking it apart further to investigate.
Has anyone seen or heard of this before? Is it possible that there's no output signal reaching the sub but instead only the 'feedback' because the pre-out jack is loose and/or broken?
Any idea how difficult or easy this would be to fix or how expensive to have someone do it if it's tough to fix?
If you can rotate the connector on the back panel, it's very likely the chassis ground connection has failed. If you feel this is the only problem with this receiver, take it to a service repair facility and ask for an estimate of repair costs before having any work performed.