Sonos playbar power supply help

[bosscharles]

Hello everyone, I've got a SONOS Playbar with a noisy power supply. Have recapped with new nichicons, upgraded the bridge rectifier but the noise remains. I've narrowed it down to the transformer which must be of terrible quality. I've come to find out that this is a fairly common issue with the Playbar. The "whine" is pretty unbearable, very high pitched and always there even when the unit is idling. Anyways, I'm trying to source a replacement transformer. Could anyone tell me where I might find the part? I've checked Farnell, ebay and RS online to no avail. There seem to be suppliers out in China via Alibaba but they require a large order. That's what I've found when I google PQ3230. Perhaps there is another term I could search for to find the unit I need? I've attached a photo of the offending unit. It has 6 legs on one side and 4 on the other. Marking reads:

182-00032
DXTPQ3230



Any pointers? Many Thanks.

[budm]

Re: Sonos playbar power supply help

May be you can try dipping it in varnish.

[bosscharles]

Re: Sonos playbar power supply help

Hi budm, could you tell me how I would go about doing that? I presume I need to desolder and place it inside a tub of varnish? For how long? What sort of varnish? Many thanks.

[budm]

Re: Sonos playbar power supply help

Just do the search for 'how varnish transformer to reduce noise'

[bosscharles]

Re: Sonos playbar power supply help

Yeah I’m just trying to understand what to do... at the moment what I understand is desolder, put in a tub/cup of varnish over night. Take out, leave to cool/dry out? Resolder onto PCB and see what happens...

[petehall347]

Re: Sonos playbar power supply help

you could try thermal paste or renew the hot glue that's already there .

[bosscharles]

Re: Sonos playbar power supply help

Yeah, tried glue..But didn’t make a difference... noise is coming from within the winding I think

[bosscharles]

Re: Sonos playbar power supply help

Fwiw, the noise is a high pitched wine and noise that sounds like an alien lol..... Do you guys reckon the varnish dip would help? From what I read that seems to be the cure for buzzing transformers... Wish I could just source a replacement

[petehall347]

Re: Sonos playbar power supply help

yes try varnish

[bosscharles]

Re: Sonos playbar power supply help

Thanks Pete, any varnish in particular? Think I've got some wood varnish in the garage somewhere. Would that suit? Thanks.

[momaka]

Re: Sonos playbar power supply help

I don't think you'll be able to find an exact replacement transformer anywhere. Most transformers are custom-made for each PSU design. (PC ATX PSUs and LCD monitor CCFL inverter transformers being the exception sometimes.)

I also concur with the idea of dipping the traffo in varnish.
Most wood varnish should be OK. DO NOT dilute with Acetone or other thinner, though, as some wire coatings may get dissolved.

Also, another thing to mention... you said you replaced some capacitors with Nichicon, but the picture does not show any of the capacitors as being Nichicon. Could you tell us more precisely (or post a picture) of which caps you replaced? On that note, where did you get your capacitors from and what series are they? I can tell you for a fact that certain flyback designs will not be happy with caps that have too low of an ESR (though caps with too high of an ESR can cause that problem as well.) I recapped a Westinghouse LCD monitor not too long ago, and it makes an incredibly loud whining noise in standby/off mode, most likely because I used caps that are quite a bit better-rated than the originals. It does work fine, though.

[R_J]

Re: Sonos playbar power supply help

Did you also replace that small cap C315?

[bosscharles]

Re: Sonos playbar power supply help

Hi RJ, I didn't, just the large ones were replaced withi nichicon branded capacitors. There were actually only two but the PCB had space for a third so I just went ahead and filled the 3 capacitor spots. Which capacitor is C315?

Did you also replace that small cap C315?

[bosscharles]

Re: Sonos playbar power supply help

Hi momaka, I will dip it in varnish. Should I just dip it and take it straight out or leave dipped overnight? Should I do more than one coating? I assume I should submerge all of it and just keep the pins outside/dry as it would make it hard to resolder onto the PCB. With regards to the capacitors I replaced. The noise was there with the original Jackon (RS PRO) capacitors so I just thought I would change them out with something better spec to see if the noise would go but it didn't. it didn't make the noise any worse though.

I don't think you'll be able to find an exact replacement transformer anywhere. Most transformers are custom-made for each PSU design. (PC ATX PSUs and LCD monitor CCFL inverter transformers being the exception sometimes.)

I also concur with the idea of dipping the traffo in varnish.
Most wood varnish should be OK. DO NOT dilute with Acetone or other thinner, though, as some wire coatings may get dissolved.

Also, another thing to mention... you said you replaced some capacitors with Nichicon, but the picture does not show any of the capacitors as being Nichicon. Could you tell us more precisely (or post a picture) of which caps you replaced? On that note, where did you get your capacitors from and what series are they? I can tell you for a fact that certain flyback designs will not be happy with caps that have too low of an ESR (though caps with too high of an ESR can cause that problem as well.) I recapped a Westinghouse LCD monitor not too long ago, and it makes an incredibly loud whining noise in standby/off mode, most likely because I used caps that are quite a bit better-rated than the originals. It does work fine, though.

[petehall347]

Re: Sonos playbar power supply help

thought i would mention i had a faulty pfc ic in a tv supply that made the transformer whine . it also drew lots of current from the mains ,, saying that the chances of it being that are rather low .

[R_J]

Re: Sonos playbar power supply help

I was looking at a similar power suppply, yours looks different, I refering to the that small electrolytic (start up cap) in the primary. but it is likely ok

[momaka]

Re: Sonos playbar power supply help

Should I just dip it and take it straight out or leave dipped overnight? Should I do more than one coating? I assume I should submerge all of it and just keep the pins outside/dry as it would make it hard to resolder onto the PCB.

I don't know about leaving it dipped an entire night, but an hour or two should probably do the trick. If you just dip it and remove right away, then varnish may not get to the inner layers/windings, and so you may still get a whine (if, assuming, that's even the reason you're getting a whining noise.) One coating should be fine, too. Most likely after that first coating, you won't be able to get more varnish in anyways when the first coat dries. So there's no point in doing more than one dip.

And yes, keep the pins clear from varnish, if you can. It's not the end of the world if they do get coated a bit by mistake, though - you'd just have to scrape / sand the varnish from the pins then before trying to solder it back to the board (i.e. extra work / minor inconvenience.)

The way high quality transformers are done with varnish is they dip them in there and then while still dipped, they pull vacuum on the transformer with an enclosure. That way, any air between the windings gets sucked out, so when they bring the traffo back to normal pressure, the varnish goes in much deeper and between all wires and layers. But I don't suppose you'd have the ability to do that at home, so just dipping for a few hours would be as best as you can do.

With regards to the capacitors I replaced. The noise was there with the original Jackon (RS PRO) capacitors so I just thought I would change them out with something better spec to see if the noise would go but it didn't. it didn't make the noise any worse though.

Well, I see you changed the 400V caps on the input with Nichicons. But it looks like the output capacitors are still the same. If they are the same Jackcon brand, I suggest you replace them too, as they are known for being quite cheap / unreliable. Even if they are not a problem now, they will eventually get there in the future. For these, you should definitely use a proper low-ESR series. Here is a list of caps that can be / often are used in SMPS:
https://www.badcaps.net/forum/showpo...7&postcount=22

[brumster]

Re: Sonos playbar power supply help

Hi there, can someone translate the markings on the transformer? I've identified a similar transformer in use on another Sonos product, see images at the link below. Might these transformers be interchangeable?

https://electronics.stackexchange.co...rent-dc-voltag

[bosscharles]

Re: Sonos playbar power supply help

Thanks a lot for the very detailed response momaka. Unfortunately, the varnish didn't solve the problem. I have a feeling it didn't make it's way into the layers/windings though. I wonder if it would make any difference if I take off the top ferrite core, apply varnish to the interior and then place back on? I think it's only kept together with yellow tape....Might just make it worse though....

I don't know about leaving it dipped an entire night, but an hour or two should probably do the trick. If you just dip it and remove right away, then varnish may not get to the inner layers/windings, and so you may still get a whine (if, assuming, that's even the reason you're getting a whining noise.) One coating should be fine, too. Most likely after that first coating, you won't be able to get more varnish in anyways when the first coat dries. So there's no point in doing more than one dip.

And yes, keep the pins clear from varnish, if you can. It's not the end of the world if they do get coated a bit by mistake, though - you'd just have to scrape / sand the varnish from the pins then before trying to solder it back to the board (i.e. extra work / minor inconvenience.)

The way high quality transformers are done with varnish is they dip them in there and then while still dipped, they pull vacuum on the transformer with an enclosure. That way, any air between the windings gets sucked out, so when they bring the traffo back to normal pressure, the varnish goes in much deeper and between all wires and layers. But I don't suppose you'd have the ability to do that at home, so just dipping for a few hours would be as best as you can do.


Well, I see you changed the 400V caps on the input with Nichicons. But it looks like the output capacitors are still the same. If they are the same Jackcon brand, I suggest you replace them too, as they are known for being quite cheap / unreliable. Even if they are not a problem now, they will eventually get there in the future. For these, you should definitely use a proper low-ESR series. Here is a list of caps that can be / often are used in SMPS:
https://www.badcaps.net/forum/showpo...7&postcount=22

[momaka]

Re: Sonos playbar power supply help

Unfortunately, the varnish didn't solve the problem. I have a feeling it didn't make it's way into the layers/windings though.

It's possible. But did the sound change at all. If not, it could also be that another part near the transformer is making the noise.

I wonder if it would make any difference if I take off the top ferrite core, apply varnish to the interior and then place back on? I think it's only kept together with yellow tape....Might just make it worse though....

No, don't try to take apart the transformer - it is certainly not held together only by tape.

The pictures of the power supply suggest the PSU uses a flyback design. This means the transformer is probably gapped (and at a very specific distance.) Once you open it, there's a chance you may change the gap distance, and that can completely throw off the regulation of the PSU or even make it not work properly anymore.

Again, my suggestion is to try to change the output caps too (or at least parallel good ones underneath them, just to make sure it's not the output caps that are causing this issue.