Polk PSW111 sub-woofer - Heartbeat

I wanted to post an issue that I found with the PSW111 sub-woofer. When the power is plugged in without any input, you hear a heartbeat noise from it. I was able to get an engineer friend from work take a look at it and narrow it down to 2 capacitors on the board. This was my second sub-woofer with the exact same issue. I am not sure if its a well known issue, but I thought I post it here. He helped me replace those capacitors and the heartbeat was gone!

My friend asked me to post this finding on here in hope that it will help someone with this issue.

Here is the spec of the capacitors and a link to one source.
105°C tolerant
.2” (5mm) lead spacing radial aluminum electrolytic.
Mouser Link

I have highlighted them in this image. (This is not my image, I found it in google search)


  • nonenone Posts: 1
    edited December 2017
    the same happened to me and more people, as can be read here. I bought the capacitors your friend recommended, thanks!

    But when I was replacing them I noticed that a capacitor was bulging, the bigger one on the bottom left (highlighted on the image below, from the link above). It is a 100uf 25v bi-polarized capacitor (CD71H). I checked all the images I could find of the board, and on all of them the cap was polarized, so I took my chances and replaced it with a polarized equivalent. I now it may not be a good idea, but for now it works. Hope it helps someone!

  • stevepstevep Posts: 73
    Thank you,

    I didn't notice this until you mentioned it. It looks like there 4 non-polarized electrolytic caps used on mine.

    C20, C48, C53 4.7uf 35v
    C41 100uf 25v that you mentioned.

    I don't think any of these are the cause of the amp motorboating but it's good information to note for anyone replacing all the caps.
  • Thank you so much
    My subwoofer is working now
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