Sub-woofer hum

[vince]

I have a pair of Atlantic Technology 352 PBM powered sub-woofers. They both developed the same problem within approximately 30 days of each other. They are about ten years old. The symtom is they started making a very loud and I mean 'drive you out of the house' very loud hum. It sounds like a 60 hz hum. One failed while watching a movie and the other failed while the input preamp was powered off. The only way to stop the noise is to unplug them. I have always left them powered up and I suspect this led to the failures.

I havn't taken them apart yet but plan to repair them myself if possible. I am an old Navy and IBM trained technitian but haven't done any serious electronic component repairs in years. I hope it is something like a blown cap or transistor. I've got my trusty DVM, understand transistor theory, and can still solder with the best of them. Any thoughts would be appreciated.

Thanks, Vince

[vtech]

Sounds like blowm main caps which should be easy to replace. Pretty much all of your subwoof's will eventually have some sort of a main cap problem.

Should be able to visually spot the bad main caps (leaking/bulgin etc)

Do remember something about an opamp or two on occasion... From what I remember, it was next to impossible to get any print or service info from them.