Axiom Home Page Forums General Discussion Technical Questions the dreaded vibration is back on the ep800

Have you tried removing the CHASSIS GROUND screw? Located between the Trigger out and Trigger in sockets.

Edit: Or putting it back in.

Hi majik,

I would agree with others here that you absolutely have a ground-loop hum. In almost all cases, it enters your system through the cable-TV or satellite system feed, so try disconnecting the cable at the input of the cable box. The hum should go away.

Here is an excerpt from my article on eliminating hum:
http://www.axiomaudio.com/tips_eliminate_hum.html

"Disconnect the incoming TV-cable or satellite feed to a set-top box or to your TV and the A/V receiver. If the hum disappears (and you don't use a satellite dish) complain to the cable-TV company. They may know what you need and supply you with a ground-isolating transformer. If they don't know what you are talking about you'll need to order a video ground isolator and install it in-line with the TV cable before it enters your set-top cable-TV box. Axiom has special wide-band isolation transformers that will not interfere with any digital TV or HDTV signal. (N.B. You CANNOT use one of these with a satellite decoder box.)"

Regards,
Alan

okay, so I unplugged the denon from the wall, and there is still vibration and hum from the woofers.. as long as the sub cable is connected to both the receiver and the sub, it doesn't seem to matter if there is current going to the denon or not.

Does this mean anything?

Hi Alan, thanks for the help, but it's not the satellite feed (I have bell expressvu). I disconnected the cable feed from the pvr and it still hums (the thing is the pvr is in one room and the receiver is in another. I don't know if it makes a difference, but the pvr is not even connected to the receiver.

I do have dsl internet though, and they came in to put a filter on my jack could that cause it?

On another note, I cannot find the ground chassis screw anywhere in all my boxes, would it be possible to get another one? Maybe I need to put it back in?

I don't think it's the cable because it was working fine in my last place (after the initial issues of course).

Other than the above mentioned steps I've also tried:

- having them plugged in different outlets
- same outlet
- same outlet using power strip
- even took the sub to another room to see if using an outlet there would make a difference.

none of these things worked.

Thanks for your input guys.

Maj, unless there's some detail that you haven't described, there was no path for a ground loop to form when you unplugged the receiver power cord. Is there something else connected to the receiver which is also plugged in, such as a player?

Majik,

Yes, the dsl connection could trigger a ground loop, so try disconnecting it to see if the hum goes away. If a sub is connected to AC power, but there is no subwoofer cable connected to your Denon and there is no hum, then there is no problem with the subwoofer.

I'm still fairly certain the hum can be traced to your PVR/DSL connections so remove those and see if the hum goes away.

Normally, the AV receiver is never the root cause of a ground loop. The loop results from other components connected to the AV receiver. And the loop can occur even when all the components are powered off, except for the subwoofer.

It takes patience and persistence to track down the source of a ground loop but it can always be corrected.

Alan

Hi John,

No, I have nothing hooked up to it yet. I did have my ipod connected via a 3.5mm jack to rca cable, but disconnected yesterday to see if maybe that was causing the problem but it's not... and I now know it's not the cable because I came across an axiom speaker cable (I guess the ppl that lived here before me had some axioms as well) and the the hum/buzz and vibration is still there.

I'm gonna look into getting another ground loop screw from Axiom and hopefully that will fix it.

any other suggestions in the mean time and in between time?

Alan,

I've disconnected the DSL and the satellite feeds - neither of which were connected to the receiver - and the hum/buzz/vibration is still there.

I don't have anything connected to the receiver and as previously mentioned, I connected the sub to my onkyo 605 receiver and that did not solve the problem; and I didn't have anything connected to the receiver then either.

How do I go about buying another ground chassis screw? Maybe that will help?

Hi majik,

Ground loops are pesky buggers. Just stay patient and be methodical.

Since you moved into a new house is there any dimmer lights, flourescent lights or computers being used that are on the same circuit as your HT gear?