Question about Sunfire True Sub MK II Subwoofer

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Sunfire Subwoofer 110 Noise on input plugin

I've had my sunfire for about 10 years (I know) but it worked great up until a few weeks ago. I got a new tv and took everything down and setup again. Once I plugged in the sub I get an extremely loud noise like when you plug a sub directly to a 110 outlet for power. I unplugged it quickly and assumed I had some sort of connection loop issue elsewhere.

After hours of narrowing everything down to only the sub and the receiver it was still happening. I tried another receiver and a small stereo with a sub rca output and it did the same exact thing but the small stereo produced a much lower hum sound (still way louder than normal "subwoofer hum").

I'm assuming there's something internally wrong now. I did have a power wire come loose inside a couple of years ago but I soldered it back on without any issues. Does anybody know what would cause this to happen? Can I replace something on the board or do I finally have to break down and buy a new sub?

PS. It's not a ground loop issue...


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This problem can also be caused by bad caps. This seems to be a real problem with this unit but considering the age I would replace the caps.

Posted on Dec 16, 2009


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A few more questions-
Does the sub hum without anything plugged into it except for power? If it makes a real loud hum almost a squeal then I think the rca cable between the receiver and the sub is dead shorted and needs to be replaced. If it's more of a low level hum, then it's a ground hum caused by many things, ie........the receiver and the sub being on different power circuits in the house.......sometimes diconnecting the cable tv feed as it enters the room while the sub is connected and humming to see if it stops........the easy fix sometimes is using a 3 to 2 prong ac adapter but lifting the ground on such a powerful amp could be a fire hazard.

Posted on Nov 02, 2008


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