diagnose my subwoofer hum.

Scott Johnson · **Posted:** Mon Jun 15, 2009 8:26 pm

I have an amplified Yamaha sub, probably 8 or 9 years old. Recently, it has developed an intermittent hum. It doesn't seem to matter what the listening volume is. Things are fine, then suddenly it starts to hum.

Needless to say, a 10" sub that starts humming will shake things a bit.

Turning the power off and back on fixes it every time. Maybe for 10 minutes, maybe for days.

I've seen faulty ground and faulty capacitors suggested elsewhere.

All soldered joints look OK, but that doesn't mean they are.

Any ideas?

Scott

Aaron Buckley · **Posted:** Mon Jun 15, 2009 9:09 pm

I ran into this with an older 2nd subwoofer I have for my home theater. Athough everything looked grounded well, I ended up needing to ground it (using an external wire) and it took care of the hum. I got the information from the techs at Crutchfield, for I had bought the sub there nearly 10 years prior :wink:

That's service for you. Hopefully that will take care of it. - AB

Scott Johnson · **Posted:** Mon Jun 15, 2009 9:23 pm

It's easy enough for me to solder a new 3 wire power cord vs the current 2 wire cord. Just pick a good chassis point for the ground.

I was hoping to take it apart and see spade terminals to wiggle, but all wires (including the main power cable) are soldered.

I was also surprised with the number of circuit boards in the thing (auto-off if the input levels are low, crossover, volume, etc).

Scott

Karl Shultz · **Posted:** Mon Jun 15, 2009 9:24 pm

You can also try replacing your wall outlet.

Aaron Buckley · **Posted:** Mon Jun 15, 2009 9:28 pm

Karl Shultz wrote:

You can also try replacing your wall outlet.

I would doubt that is the problem. I had the same issue with this subwoofer in 2 houses prior to the ground wire fixing it. - AB

Frank Catena · **Joined:** Wed Aug 27, 2003 1:08 pm **Posts:** 418

It could be either the outlet or the device but the ground wire that Aaron suggests should solve the problem. This link provides more info than you need, but figure 6 is the important one. The text suggest running the ground from an external grounded connection (i.e. screw) for safety.

http://www.jensen-transformers.com/an/an004.pdf

Frank

Scott Johnson · **Posted:** Thu Jan 14, 2010 11:20 am

Saw this on a search for other things.

Turned out to be a bum RCA cable to the sub, intermittent short. It was easy to diagnose when the cable split into two pieces.

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diagnose my subwoofer hum.

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