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.
47uF
63V
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)
vac6se64vn0x.jpg

Comments

  • nonenone Posts: 1
    edited December 2017
    Hi,
    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!

    pxihufqqqm4e.png
  • stevepstevep Posts: 186
    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
  • You're a lifesaver! My PSW111 would cut off during heavy action scenes in movies, occasional heartbeat, etc. Replaced those 2 capacitors and its playing as loud as new. Thanks for the info!
  • EepEep Posts: 7
    Polk needs to accept their subwoofers doing this and fix/replace them. This is apparently a rampant problem with Polk subs!
  • Thanks for the tip. I replaced the two caps listed and my heartbeat problem disappeared! What did you guys use to replace the "glue" that was holding down all the board screws?
  • stevepstevep Posts: 186
    Hot Melt Glue works and won't corrode anything.
  • CKFCKF Posts: 1
    Same “heartbeat” issue with my PSW111. Bought in 2013 and started acting up 2 days ago. Upon inspection there were no visible signs of damaged caps but I figured it was worth a try. Some gas and $1.50 for both caps as noted above resolved the issue. Saved me hundreds for a new sub! Many thanks!
  • seabeanseabean Posts: 2
    I'm not an electrical guy, but my sub had stopped working. The attached pictures shows the same capacitors as the picture above. Does this look like a capacitor issue?721sfwqm8u2f.jpg
  • seabeanseabean Posts: 2
    Another angle.6gqe5lzhgg2f.jpg
  • fsolfsol Posts: 2
    Your note is a life saver. I have a same issue, and it is driving me crazy. Now I knkow how to fix it.
  • fsolfsol Posts: 2
    I managed to replace the capacitors without removing the board which seems to be really hard. For doing this, I bent the capacitors so that a little bit of their wire stays out, and then pulled them out, and soldered the new capacitors to those wires. Works perfectly in my case. Thanks again for your life saving discovery about changing these capacitors.

    uh7j0n232qqq.jpeg
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