PSW-125, capacitor gassing off?

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PaulinS
PaulinS Posts: 7
in Troubleshooting
So my PSW-125 gave up the ghost, the seemingly standard problem of constant noise regardless of switch position, humming, beating, basically everything except what you actually want to hear. I popped the amp out of the back and it sounds and smells like a capacitor gassing out. I can't get the last screw out of the board mounts to get behind it and try to figure out which one is blowing, is there one that is commonly known to fail? I'm not overly keen on replacing the entire module, frankly for the money that costs I'll just go get a new (non Polk) subwoofer.
Cheers,
Paul.
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  • PaulinS
    PaulinS Posts: 7
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    I managed to get the board out. There are wooden dowels glued in place to use for board supports which I certainly didn't expect to see in anything above some store-brand lo-fi speaker. Anyway, now need to figure out what's blown.
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  • Clarkel
    Clarkel Posts: 1
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    Did you find the capacitor that was blown, I have the same problem. This is my second one in two years.
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  • PaulinS
    PaulinS Posts: 7
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    There are actually three of them showing signs of failure, either bulging or leaking. I haven't had a chance to unsolder them, get replacements and throw them in yet to see if that fixes it. There may be some other component that caused them to fail, but capacitors do just go sometimes, and one failing can ripple to others.
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  • PaulinS
    PaulinS Posts: 7
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    I will try a grab a photo later and highlight the blown ones, but your best bet is to look at yours as it could be different. It's usually pretty obvious if a capacitor is gone, diodes or transistors are swines to troubleshoot though. I think if my initial fix doesn't work then I will get a replacement amp unit from another manufacturer and hook it up to the Polk cone/enclosure.
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  • PaulinS
    PaulinS Posts: 7
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    So, the three that are gone:
    C14, 120uF 63v
    C39, C39, 47uF 63v
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  • PaulinS
    PaulinS Posts: 7
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    Replaced, working. $3 in parts.
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  • txcoastal1
    txcoastal1 Posts: 13,519
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    Good news

    Any documentation would those in the future if you could post

    Thanks
    2-channel: Modwright KWI-200 Integrated, Dynaudio C1-II Signatures
    Desktop rig: LSi7, Polk 110sub, Dayens Ampino amp, W4S DAC/pre, Sonos, JRiver
    Gear on standby: Melody 101 tube pre, Unison Research Simply Italy Integrated
    Gone to new homes: (Matt Polk's)Threshold Stasis SA12e monoblocks, Pass XA30.5 amp, Usher MD2 speakers, Dynaudio C4 platinum speakers, Modwright LS100 (voltz), Simaudio 780D DAC

    erat interfectorem cesar et **** dictatorem dicere a
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  • Dennis Gardner
    Dennis Gardner Posts: 4,861
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    Common failure, Thanks for listing those that went out, it will help others when they search the forum for an answer to their problems.

    Just for future owners: Capacitor List

    So, the three that are gone:
    C14, 120uF 63v
    C39, C39, 47uF 63v
    HT Optoma HD25 LV on 80" DIY Screen, Anthem MRX 300 Receiver, Pioneer Elite BDP 51FD Polk CS350LS, Polk SDA1C, Polk FX300, Polk RT55, Dual EBS Adire Shiva 320watt tuned to 17hz, ICs-DIY Twisted Prs, Speaker-Raymond Cable

    2 Channel Thorens TD 318 Grado ZF1, SACD/CD Marantz 8260, Soundstream/Krell DAC1, Audio Mirror PP1, Odyssey Stratos, ADS L-1290, ICs-DIY Twisted , Speaker-Raymond Cable
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  • PaulinS
    PaulinS Posts: 7
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    Sorry, typo from using a phone, C38 and C39 are the 47uF ones.
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  • rpereira
    rpereira Posts: 5
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    I did not find c38,c39 and c14 at my psw125 board. It seems to be another revision of the board. Could you help me please ?
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  • pitdogg2
    pitdogg2 Posts: 27,787
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    rpereira wrote: »
    I did not find c38,c39 and c14 at my psw125 board. It seems to be another revision of the board. Could you help me please ?

    Maybe provide a good picture so we can see what you have.
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  • rpereira
    rpereira Posts: 5
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    pzn5es33ac6m.jpg
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  • SeleniumFalcon
    SeleniumFalcon Posts: 4,359
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    Let me see if I can find some help.
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  • SeleniumFalcon
    SeleniumFalcon Posts: 4,359
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    I'll email you a schematic.
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  • rpereira
    rpereira Posts: 5
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    I got the email, thank you so much.
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  • rpereira
    rpereira Posts: 5
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    Sorry , i noticed my psw125 board has PCB # 600157 REV 0. You sent PCB # 600170-5 REV 5.
    My board uses L7815cv and L7915cv regulador but i did not find at schematic you sent.j921jqi7hfxs.jpg
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  • SeleniumFalcon
    SeleniumFalcon Posts: 4,359
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    I'll check.
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  • SeleniumFalcon
    SeleniumFalcon Posts: 4,359
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    Unfortunately that is all the information Polk has on that amp.
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  • rpereira
    rpereira Posts: 5
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    ok, thank you.
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  • Mike_476
    Mike_476 Posts: 1
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    I have a similar problem . A schematic will be helpful. My board is PCB # 600170-5.
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  • SeleniumFalcon
    SeleniumFalcon Posts: 4,359
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    I'll send it.
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  • dudaindc
    dudaindc Posts: 4
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    SeleniumFalcon wrote: »
    I'll send it.
    I have the same issue and having the schematics would certainly help.
    May I have a copy, please?
    Thanks a million!

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  • SeleniumFalcon
    SeleniumFalcon Posts: 4,359
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    I'll send it.
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  • dudaindc
    dudaindc Posts: 4
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    SeleniumFalcon,
    Files received.
    Thanks for helping me out.
    I really appreciate that.
    Cheers!
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  • SeleniumFalcon
    SeleniumFalcon Posts: 4,359
    edited January 2022
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    You're welcome! Glad to be of help.
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  • joaosg
    joaosg Posts: 1
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    Hi SeleniumFalcon,

    Can you send the schematics to me? Just got the same issue..

    Thanks

    Joao
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  • SeleniumFalcon
    SeleniumFalcon Posts: 4,359
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    Hi Joao,
    It's on its way!
    Regards!
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  • mithril
    mithril Posts: 3
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    Hey SeleniumFalcon, can I get a copy of the schematics too?!

    I have a PSW111 with a blown fuse. Disassemble, inspect, 600157 board. R22 green thermistor has a hole blown in the side and the yellow cap next to it had smoke residue on it. Replaced the thermistor and all the caps except the 2 big mains caps. Powered it up, new fuse blew. Desoldered the bridge rectifier, it tests out fine.

    Will post again once I solve whats wrong :)
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  • SeleniumFalcon
    SeleniumFalcon Posts: 4,359
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    I've sent it.
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  • mithril
    mithril Posts: 3
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    Thank you! Unfortunately the 600170 board is not similar in design to the 600157, but it was worth a shot. The good news is I found the fault in my amp which was a shorted IRF730 mosfet. Searching "IRF730 sub" I ended up learning the 600157 amp design is used in Klipsch RW-12 and PSB SS5i which I was able to find schematics for both. Hope this helps someone else who might end up here!
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