I have a small Polk Audio PSW111 subwoofer that is used for home theatre duties which has recently developed a strange noise.

It can best be described as a regular soft heartbeat sound which is faintly audible at all times even with the cable from the AVR disconnected. It will only stop if I disconnect the power cable.

Checking on line there is quite a bit of talk about this fault but the only recommended fix offered is to get a replacement from Polk Audio.

Mine is way out of warranty so this option is out of the question.

Also from this online chat it seems to be related to faulty capacitors on the psu circuit.

Any suggestions from you circuit gurus as to how to fix this. If its just a matter of replacing some caps that's no problem, but how to find out which ones !!!!

Aha, I think I have just found the answer.

Google is your friend .

The attached photo shows the culprits on a posters psw111 which had the same complaint.

They are a pair of 47uF 63v caps rated at 105c tolerance.

I wonder if a higher tolerance is in order ?