HELP!!!

[Hborea]Raistlin

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Nov 19, 2006
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Benjamin Thompson
Hi all--I know absolutely ZIP about speakers and/or anything to do with electronics.. I've got a problem with the subwoofer in our home theater system, though. It (was) hooked up to our receiver via coax(?) cable (Monster brand), though we had something of a 'splitter' for the inputs (only one out on receiver)... Anyways, our cat bumped into those inputs & the sub just started humming extremely loud........ I have NO clue what to do. I've unplugged the inputs, unplugged to sub, etc. I then plugged the sub back in (not to receiver, just electrically) and it sits there humming away.. Any help would be GREATLY appreciated!!!

 

Robert_J

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Robert
As a test, remove the splitter and connect the sub cable to either of the inputs. If the hum is gone, then the splitter is the problem. It is not needed.

If the hum continues, replace the sub cable with any other cable. If it works, then the sub cable was the problem. Just use the one that works. If you really want to replace it, choose something other than an over-priced Monster.

If the hum continues, then the cat may have pulled the cable causing the input to be bent. Since you sound like you aren't comfortable in taking apart your sub, I'll leave those directions up to someone else.

-Robert
 

[Hborea]Raistlin

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Benjamin Thompson
I've already got it taken apart, Robert---first two steps didn't work... I can see the inputs are connected to a PCB, but have no idea what might be 'bent'.. or I just am not looking for the right disconnection(?) It's got low-level inputs as well as high-level, but the receiver (as far as I can tell) doesn't have speaker-wire outputs for a sub (for the high-level). Any ideas?
 

[Hborea]Raistlin

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Benjamin Thompson
I've figured out that something inside the sub is wrong. There's a light on it which is red when no signal is present, turns green if there is. When I plug in to the inputs, light turns green--but sub still sits there and hums, no sound from the receiver. Any ideas anyone???
 

[Hborea]Raistlin

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Benjamin Thompson
Update: The sub was NOT the problem--it's the receiver. After troubleshooting above, I finally plugged the sub straight into the DVD player & waaalaaah... problem-area recognized. Now, can anyone help me figure out what could have happened to the Sub-out on the receiver??!? I can't believe all these people are on this forum ALL the time & ONE person had the knowledge/advice to help the original problem.... Thanks in advance--
 

homthtr

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Steve
The reason a sub hums....




It doesn't know the words!




ok old home theater joke... had to get it in!

What's the make and Model of your Receiver... I can probably get you though some more troublshooting.
 

Jeff Gatie

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Aug 19, 2002
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When a sub hums when attached to one component and not to another, it is usually an electrical ground loop that is to blame. Since the receiver has many more outputs than the DVD, it would make sense that the receiver is to blame. You could use the old "3-prong adapter" trick, but that is a cheat (you end up with an ungrounded sub). If you still want to try it, just get a 3 prong to 2 prong adapter plug and plug your sub into the wall socket with that.
 

[Hborea]Raistlin

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Benjamin Thompson
Thanks for the info Jeff, but I have two subs--one is grounded (3-prong) while the other is not (2-prong). Neither one of them works with the receiver..... Which happens to be a Pioneer VSX-815 Audio/Video Multi-Channel Receiver, homthtr. Any further ideas/help would be GREATLY appreciated, as I have no idea what the problem could be, other than an internal short/burnout somewhere in the receiver, directly linked to the Preout for the Sub...
 

[Hborea]Raistlin

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Benjamin Thompson


CORRECTION: I plugged the wrong sub into the DVD player--the one which wasn't working, well, it still hums no matter what it's plugged into.....
 

homthtr

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Steve
First with just the Sub plugged into the wall and your Sub cord connected to the sub without plugging into the receiver does it hum?

If not good...

Touch the tip of the sub plug that goes into the receiver with your thumb.
Does the sub hum? If yes then good...

Next I want to make sure that you are plugging the sub into the sub preout and not the DVD Pre - in on the back of the Receiver. The Sub Pre-out is located at the bottom just to the left of the DVD S-Video in. Just underneath the Monitor out. (NOT ON TOP WHERE THE DVD 5 Channel input is).

Connected Correctly? Yes....

Hum??? NO.... Great Problem fixed

Hum??? Yes... OK lets keep going....

Unplug the sub from the sub preout and move it over 2 Rca Jacks to the left
Which should be the CDR/TAPE Left Channel out.
Plug the Sub in there

HUM? no... then there's a short in the subpreout in the receiver. needs to be serviced

Hum Yes...... I need to be serviced!.... cuz then I'm stumped.
 

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