Aftermarket amp for Kef psw2150 - AVS Forum
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post #1 of 17 Old 10-03-2011, 09:46 AM - Thread Starter
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I have the psw2150 sub made by Kef. It's my THIRD one after the first two amps died. The sub has just died again (loud buzzing even when not connected to the receiver). This appears to be a common problem with these subs (amps). Anyway, I'm going to buy a different brand of sub as a replacement. However, it seems to be a shame not to use this sub for something (maybe in the den). Therefore, I want to put in an aftermarket amp. I see Dayton makes a 250wt plate amp.

Does anyone have experience with this (or similar) type of thing? Thanks.
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post #2 of 17 Old 12-23-2011, 12:53 PM
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I realize this is an old thread, but I JUST finished fixing my amp (had the buzzing sound), and it was very easy. It was also really cheap. The new cap required cost $1. I can lead you through how to fix it if you want.
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post #3 of 17 Old 12-27-2011, 07:59 AM
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I have the buzzing problem on my 2150. If you could walk me through the repair i would be most appreciative
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post #4 of 17 Old 01-06-2012, 01:39 PM
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Hi,

I would like to know any info on replacing amp in KEF PSW2150 also.
Mine died for the second time, a year or so ago - it's been sitting since then as not wanting to spend the money the shop charges.
If I could replace with after market or repair inexpensively - that would be great.

The shop had said he had a time opening the unit up. Is that not the case?
Id rather repair it over having it sit ant longer or selling it for parts - since I've already invested in it twice.

Any help would be appreciated.

namaste
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post #5 of 17 Old 01-10-2012, 07:08 PM
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Hey- I don't regularly check this site, so sorry for not responding earlier. Anyway, the "buzzing" fix is fairly easy. The C52 capacitor (location on the pcb, not a model number or rating) is located just above the two large smoothing caps on the amp.
First you need to locate a 47uF 100v 105degree radial capacitor. The one that has failed is a 63v 47uf 85degree one, but you need to "upgrade". I didn't have any place nearby that sold them, so I bought two from ebay. They cost $2 shipped.
Second, you need to take out the plate amp from the box, remove all the wire connectors connecting the amplifier part to the pre-amp part (the amplifier itself is the pcb that has the two large caps attached, and the transistors that are connected to the large heat sink.), and then unscrew the amp from the back plate.
I found that I was able to unsolder the C52 cap from the amp pcb without disassembling any more than this. If you're not able to access the posts underneath, then you'll need to unscrew the pcb from the bracket as well as unscrew the transistors from the heat sink. My advice is try first before going through this extra work. Make sure you note the polarity of the cap before removing it, and install the new one in the same orientation. Once the new cap is in, you just need to reassemble everything and plug it in.
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post #6 of 17 Old 01-11-2012, 08:01 AM
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I had the same problem... Thanks marvin, your advice just worked for me!
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post #7 of 17 Old 02-06-2013, 06:17 PM
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Old thread, but I want to try this and the ebay listing is gone. Would this work?

http://www.amazon.com/Nichicon-Thru-Hole-Aluminum-Electrolytic-Capacitor/dp/B0058V13QQ/ref=sr_1_1?s=industrial&ie=UTF8&qid=1360203386&sr=1-1

Nichicon 47uF 100V Thru-Hole Aluminum Electrolytic Capacitor RADIAL 20% (Bag of 5)

Thanks!
Rich
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post #8 of 17 Old 02-09-2013, 12:35 PM
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HOW ABOUT A PICTURE OR VIDEO FOR A LAY PERSON.smile.gif
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post #9 of 17 Old 05-28-2013, 11:40 AM
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I had this problem on my PSW2150. Marvin's description was perfect and I was able to repair mine. How long it will last for, who knows.. As I understand it, his sub completely died shortly after his repair as noted on another forum.

Here are the pics uploaded to imgur: http://imgur.com/a/LYgnJ

A couple notes about my repair job:
  • Only the speaker leads hold the back panel to the sub box after you've removed the screws holding it on. They are in the center of the board and mine were quite tight. I had to use gentle but firm pressure to unplug them from the board.
  • I could not remove the wires connecting the amp to the pre-amp etc. I think the plugs were soldered or glued in. So, I improvised and rested the amp at an angle on top of the pre-amp so I could get to the solder points underneath, without having to disconnect any wires (except the one plug right beside the capacitor itself)
  • I used a standard Weller WES51 Analog Soldering Station - just like this one: http://amzn.com/B000BRC2XU
  • I did have to add a touch of fresh solder as I had wicked off most of the original when removing the old capacitor
  • The capacitors I bought had very long legs on them - I trimmed them to fit a little better.

HTH somebody in the future. Feel free to post or pm if you have any questions.
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post #10 of 17 Old 06-24-2013, 11:10 AM
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ninja6o4,

Your post and the pics are friggin' awesome. Thank you. I have my capacitor on order and my fingers crossed. Your PSW2150 still holding up after that work?
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post #11 of 17 Old 06-24-2013, 01:15 PM
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Quote:
Originally Posted by Fido_One View Post

ninja6o4,

Your post and the pics are friggin' awesome. Thank you. I have my capacitor on order and my fingers crossed. Your PSW2150 still holding up after that work?

Happy to report that the sub is still working great as of yesterday. Definitely worth trying at the very least, considering the alternative is a $200+ replacement. Good luck!
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post #12 of 17 Old 06-26-2013, 04:58 PM
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Quote:
Originally Posted by ninja6o4 View Post

Happy to report that the sub is still working great as of yesterday. Definitely worth trying at the very least, considering the alternative is a $200+ replacement. Good luck!

Huh! It worked! Had been so long since I had a soldering gun I was sure I had made a mess of it. I had a call into Kef, and they were saying a solid 180 + shipping to look at it, which I couldn't afford - this post of yours and your pictures gave me the confidence to give the DYI a go. Thanks again!
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post #13 of 17 Old 06-26-2013, 06:16 PM
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Good stuff! I'm glad to hear the pics and OP helped. Enjoy hearing that bass once again smile.gif
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post #14 of 17 Old 09-17-2014, 08:17 PM
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After a year of being KEF-less, I decided to take a stab at replacing the C52 capacitor in my 2150 PSW after my Polk Audio replacement-sub started making noises, too. It was okay, but I missed the deeper richer bass and much better performance of my KEF. I'm happy to report that my attempt at fixing my sub was a resounding success! However, I did notice that the voltage on the speaker output terminals measured 139 to 140 mVolts, a bit more than the 100 mV that the instructions mentioned. Nonetheless, my 2150 is working like a champ again! Thanks for the detailed instructions!

Last edited by bbigby64; 09-20-2014 at 04:36 AM.
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post #15 of 17 Old 09-18-2014, 07:56 AM
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Glad to hear this is still helpful for people out there.
Just to update: More than a year after my resolder job and my subwoofer is still pounding as hard as ever

If anyone else out there has this issue and is considering a fix, my advice: do it!
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post #16 of 17 Old 09-20-2014, 04:30 AM
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Quote:
Originally Posted by ninja6o4 View Post
Glad to hear this is still helpful for people out there.
Just to update: More than a year after my resolder job and my subwoofer is still pounding as hard as ever

If anyone else out there has this issue and is considering a fix, my advice: do it!
Yes, absolutely! Fix it!
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post #17 of 17 Old 10-02-2014, 02:01 PM
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Yes indeed. I printed the pictures and instructions, ordered the capacitor online, and bought a nice soldering iron.

I hadn't soldered since high school (about 30 years ago), so the disassembled Subwoofer sat there for a few weeks,
while I worked up the nerve. I gave it my best shot and put it all back together.
Yes, the lead wires from the speaker to the amp are *short*!

I powered it up and didn't really expect it work. No buzz, that part's good... and then lo and behold: the BOOM!

I got my Bass back! Plus the knowledge that I can actually do a simple solder. And saving the cost of a new Sub-Woofer.

THANKS ALL AROUND!
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