KEF PSW2000 subwoofer repair

[@PileOfEmptyTapes]

"I am strongly suspecting the preamplifier since the power amplifier isn't on fire..." _Classic._ Troubleshooting 101 right there. :D

[@SidneyCritic]

Thanks for repairing it because repairs are interesting to watch, and thanks for editing out the slow bits so it watchable.

[@craignehring]

Glad you decided to repair this. I love the surgical approach to cleaning up the PCB. The pair of VR caps with the low rating is a laugh. Me wonders if they really do this to create planned obsolescence ?. Crazy

[@ruaraidhmcdonald-walker9524]

Great repair! Am just in the middle of rebuilding mine after the main power supply caps dried and then whole thing including the poweramp drivers went bang. Have replaced all caps, heatsinked everything, new output stages and now just getting it back up and working again, arguing with the protection circuit at the moment as it's not engaging the output realy. All good fun and games, wish I had all you lab kit!!

[@brub5174]

I have the kef psw2500. Nearly all my capacitors are shot.(even some on the pre-amp) Measured all of the ESR. Needed to replace nearly all of them, will be a good job😅 but looking at your repair i am more confident that it might be a solution, because i read somewhere that bad caps can't make your Subwoofer go silent, only buzzing or such. Let's see tomorrow or friday when the parts arrive. (Should have watched your video first so i would jave got the 25v instead of 16v 😅) Thanks for sharing your video, it was helpful, I also stole the oscillator from work but fingers crossed I dont even have to use it

[@Seegalgalguntijak]

I am totally amazed by this kind of electronic knowledge. It is so useful! I wish I had that kind of knowledge about electronics myself so I could fix stuff just like that...

[@ChaosHusky]

I have the slightly newer version of this sub.. And they are a right pain to work on! Protection circuit is doing its job too well in mine, even though the amp is actually running fine it won't turn on the relay lol does seem a little down on power but this whole thing was free and its getting boring!

[@FabianEason]

This is the third sub fix I've watched where the rail regulator caps are the culprit

[@brub5174]

This should get upvoted

[@anthonyvalente8203]

Great video. I've got the KEF's big brother, the PSW3000 and I've had issues recently with a dud filter cap in the PSU. This is a great reference should I get further issues on the pre-amp side.

[@BenjaminEsposti]

16V caps on a 15V rail? You should see the cheap YIHUA bench PSU I have. When it is at the highest transformer tap (for maximum output voltage), the voltage on the 50V filter capacitor is almost 60V!!! Granted, it's a Rubycon cap, and appears to be genuine, and it has run for hours at the highest transformer tap without blowing up. I think the capacitor has reformed the oxide layer to that voltage.

[@saarike]

Excellent repair! Heh 220uF, 16V caps in 15V line - wrong place to save money on factory.

[@travelandfishingtrafish]

how about same subwoofer KEF PSW 2000 all fine, except when you plug the speaker input it's not working? THANKS

[@myplaguesify]

Did you also replace the two twin big capacitors? seen at 2:04

[@FFcossag]

I don't think so, though those often fail too.

[@myplaguesify]

@@FFcossag coz i have the psw 1000.2 with same design and board of psw2000 and still working fine,does all units affected? im worried bout this.

[@FFcossag]

Probably, but I don't know.

[@robbieaussievic]

....... Excellent detection work, you're a gentleman and a scholar, (Despite what Interpol say).

[@oggyosbourne]

Hi FFcossag What is this for music you are playing around 7:35?

[@robinyoyoyo2034]

The song is called: CombatPlayer - Off Time

[@oggyosbourne]

Thank you!

[@Darieee]

Is that one of those big-ass touchscreen info-point type TVs ?

[@eigenvector7035]

Finally! The secret ESR meter ;) Why arent you showing it!

[@pacoosorio5278]

Hola tengo uno igual pero solo me suena el altavoz central los demas altavoces no suenan me puede ayudar que averia tiene gracias

[@abhichopra7217]

Hello mate, I am new with all these things so my question is I have kef PSW 2000 fuse blew and then put new fuse no power but very little hum sound from the main transformer and its become hot so for transfer its normal warm or hot When it's working? so would you think what is a problem with this so no power but transformer working sound like but hot? so will you please let me know Thanks

[@Botototski]

Really nice videos buddy... I got this sub dusted off and wanted to repair it in my spare time... care to share or suggest which components should I buy? I got the same burnt out opamp with the green capacitor attached to it so thinking of replacing them together with the 2 capacitors. I'm not an electrician but I know basic soldering. So I wanted to replace the opamp (BA4560), green capacitor (224k) , 2 capacitors (220uf 16v) to start with.

[@FFcossag]

Just use components identical to the ones already installed, except not broken. ;)

[@Botototski]

Got it except for the green capacitor (224k) connected to the opamp... not sure what to look for and what does K means?

[@brianwilliams9100]

Thanks for the video! I have a kef 2150 sub that i bought recently as a package deal stereo system. Coupled with a Nice Denon network AV Receiver, center channel speaker and some nice B&W front speakers i was looking forward to some nice sound. I trusted the guy when he said that it all worked. Everything but the sub is intact. except this buzz coming from the bottom of the sub. I would conclude from you video that its the transformer. However after opening the cabinet I noticed the two main caps look to be bulging. One cap has a broken seal at the top. Would you recommend replacing these as a start? I don't have the test equipment you have nor the knowledge. I am an electrician but a lot of this is over my head. I can send pics or video if you could help. Thanks again for the video. Learned a lot...Cheers!

[@FFcossag]

You could try it. If it's similar to this one, then perhaps try replacing the ones I replaced as well.

[@twocvbloke]

It's amazing how problematic caps can be, especially when a Mr. Bodgit comes along and puts underrated parts in place of the originals... :P As an aside, that touchscreen PC would look good hung on a wall and used as a fancy whiteboard... :D

[@FFcossag]

I'm strongly considering sacrificing some bench shelving in favour of the touch screen PC, because it's just insanely practical for schematics. Stay tuned.

[@t-dubbiedubb5028]

hello there.....I have a jbl prx718xlf (powered active subwoofer) that has an amplifier issue...what is doing is as I powered it up I noticed a slight hum coming from the sub and when the cooling fan kicks on I can also hear a slight winding sound that's coming out of the sub as well too....I also try putting on a clean signal I noticed a very horrible distortion going thru the sub even if I tried to adjust the volume nothing changes and as I powered it down the sub was making a thump ( kinda like a loud pop sound) as I powered down the amplifier...any idea of what can cause this problem? Thanks.

[@FFcossag]

The two most common issues on subwoofers are bad caps and conductive glue making things go haywire. I can't say anything about your specific unit.

[@t-dubbiedubb5028]

FFcossag ok I'll be sure to do that to see if it fix the problem..... I also noticed when I took the amplifier apart and to try to determine whether its the preamp board or the main power supply board itself thats causing this weird noise......And as I swap the preamp board into a working sub with the same model just to see if the problems follows the noise was gone and function normal so Im assume it could be the main board itself that's causing problems but then again I can be wrong.....I even try disconnecting the preamp board from the main board to see if the noise stop and it did which leads there is something going on to either the preamp or the main board itself but I will try to check some caps and also try to see if I can remove the glue to see if it helps........I also have a video on my channel if you will like to see the problem that I have so that way you can see the problems better than I can explain it......there should be 2 videos.

[@MrStingraybernard]

Got a kef psw 2150 took driver out and that works but subwoofer does nothing

[@damacc8365]

Really enjoyed you taking us through the troubleshooting steps for this problem!

[@FFcossag]

Glad to hear it, I hope it'll save someone some time, some time.

[@humbledeer]

Why does it look like you soldered leads on your probes when you measured the caps? Is that an accident, or something slightly smarter?

[@FFcossag]

It's sowing needles, the probes need to be extremely sharp since we're measuring resistances down to

[@humbledeer]

Can you elaborate on why the normal probe points can't measure low resistances? Is it to do with the surface area?

[@FFcossag]

You can't reliably pierce the oxide/impurity layer that covers literally everything you want to measure. You need the really sharp (and clean) point in order to actually make a low resistance connection to the metal below. If you shove a normal probe against a solder joint, you'll have 100-200 mOhm of random fluctuation as you're measuring, since all those impurities are getting shoved around as you hold the probe. It's not an issue as the meter will average it out and doesn't usually even have the resolution to quite tell, but when your meter has a 1 mOhm resolution and a 50 mOhm change can be the difference between pass/fail of a component, it starts to matter.

[@humbledeer]

Ah, that makes total sense! Thanks for elaborating. :)

[@robinyoyoyo2034]

What is the song at 7:35?

[@FFcossag]

Off Time by Combatplayer.

[@robinyoyoyo2034]

Thanks.

[@RWL2012]

This video is NOT in your "audio videos" playlist.

[@FFcossag]

Oh well.

[@Chriva]

What's the whining in the background? :D Locked up a genie in the fridge? ;)

[@FFcossag]

No, it's a girl tied up in the laundr- I mean yes, a genie in the fridge.

[@alfoncejean8826]

FFcossag good to know she is out of the dryer.

[@First2ner]

Filtering 15v with 16v cap is not a problem, is it stable 15v AFTER regs.... not the best practise, but that caps were overheated by regulators itself, temperature was the cause of problems here, not 16v rated caps. I bet they were also 85C caps

[@FFcossag]

Not true; electrolytic capacitors last longer with lower voltages applied. There's some fancy scientific reason for this that I learned in school, but I'm too lazy to dig it up.

[@First2ner]

ok, true, but even if they were 25v rated, but are next to very hot regulators (if they are that hot?), then temperature will have more impact on life span of the component than voltage, which is still well in within rating. Everything is better being far from limits, but heat is degrading component more than voltage, wouldn't you say so?

[@FFcossag]

It depends on circumstance. The regulators on this board actually don't run all that hot, so in this particular case I'd say the voltage across the capacitor had a much larger impact on its lifespan than you usually find.

[@fouzaialaa7962]

when did you get a giant ass touch screen ???................ that is awesome!!!

[@FFcossag]

What can I say, sometimes you just get a giant ass touch screen.

[@SuperBrainAK]

yea that thing is epic for schematic viewing!

[@dosgos]

That KEF sub looks to be garbage. But made for a great video. Now that it is working, it will be great addition to the lab. Looks like your issue was not the popular cheap fake chinese caps but bad industrial engineering. . .

[@FFcossag]

I'd wager the issue was a combination of both; had the caps said Nichicon, I doubt they'd have failed.

[@davefisher793]

KEF as a rule make good speakers & subwoofers. They have however been let down by minor amplifier design / component rating issues such as this. Particularly on the PSW range of subs.

[@dosgos]

Agreed. But when these "minor" issues leave consumers with bricks, the issues are not so minor. I suppose it helps the landfill business and helps future sales. . .

[@FFcossag]

I'm aware of KEF's reputation, it surprised me when I heard how utterly terrible this thing sounds, lol.

[@MrCacciLLo]

Yes, the temperature there boils any cap. Nichicon boils like any other. Just really really bad engineering

[@thrilled2bits]

I have exactly the same subwoofer. Blew when i accidentally switched from 240v to 110v on the back without looking to switch on the woofer, is there an internal fuse i can change?

[@zx8401ztv]

Nice repair :-D, poor quality and wrong selection of crap-acitors. Oh, we dont want your smelly esr testing system.. he he :-D :-D

[@FFcossag]

There will come a point when you can have it ... I just don't know when. ;)

[@zx8401ztv]

Ooow you tease :-D I have thought about buying a cheap atmega based one, i know it would not be exact, but anything would be better than nothing :-D

[@FFcossag]

Those cheap testers are good enough for most things, mine's special because it works on ultra low voltage, under 200 mV P-P, so it can measure caps in almost any circuit. I so wish everyone could have one.

[@zx8401ztv]

Yes it would be nice, but there are atmega ones around. I have an ancient charge up tester that ive rigged to bang ten times the current through a cap to test it, it seems to show a very low capacitance with bad esr caps, and new caps show the same capacitance on any range, no supprise. But a propper esr meter is still a thought.