Polk Audio PSW111 Subwoofer - no power

[Bterrier]

So I picked up a polk audio psw111 from the thrift store for $10. Doesn't power on, knew this going in but figured it was worth the $10 to see if I could get it working.

The fuse at the iec socket is blown....I have a few on order. (1.6a 250v)

Im wondering if replacing the fuse would resolve this or if there is an underlying issue. I'm assuming the fuse will blow again when I replace it because I don't feel it would blow for no reason.

Looking for insight and what steps to take to troubleshoot this issue.

TIY

[dmill89]

Re: Polk Audio PSW111 Subwoofer - no power

So I picked up a polk audio psw111 from the thrift store for $10. Doesn’t power on, knew this going in but figured it was worth the $10 to see if I could get it working.

The fuse at the iec socket is blown....I have a few on order. (1.6a 250v)

Im wondering if replacing the fuse would resolve this or if there is an underlying issue. I’m assuming the fuse will blow again when I replace it because I don’t feel it would blow for no reason.

Looking for insight and what steps to take to troubleshoot this issue.

TIY

There is a good chance the driver transistors are blown, those polk sub amps are notoriously underbuilt (especially older ones). There may also be conductive glue if it is older (brown glue that carbonizes and turns dark-brown/black and becomes conductive with time/heat). Polk also likes to use really cheap caps (crap like Jun-Fu, Fuhjyyu, etc.) in these amps that can fail as well. I'd start by testing the driver transistors (with a multi-meter/ transistor tester or just pull them and see if the fuse still blows) and also check the bias resistors and caps. If there is conductive (dark brown/black) glue scrape it off the board. If it is new enough to have a switching power supply that may have failed components as well.


Dayton (parts express house brand) and others sell replacement sub amps if all else fails, but at $50+ it probably isn't worth it (you can often find decent working subs on ebay for that price).


After owning a Polk powered sub (don't remember the exact model but it would have been circa 2005-2006 and failed in 2012) that blew its amp and an seeing what a steaming pile of crap the amp (cheap caps, conductive glue, undersized heat-sinks, etc.) was in a ~$300 sub (the Sony I replaced it with which was half the price has a much better built amp) I'll never buy another Polk sub/powered speaker (I could understand that build quality in a <$100 off-brand sub but not in something positioned as a "premium" product). Their un-powered speakers may be fine but I don't the trust the powered stuff.

[Brucetafer]

Re: Polk Audio PSW111 Subwoofer - no power

I fixed mine after replacing all the smaller caps, theres a TON of write ups on the PSW 110+, the amps are junk.. I ended up rebuilding the entire amplifier with quality components..

[Bterrier]

Re: Polk Audio PSW111 Subwoofer - no power

I fixed mine after replacing all the smaller caps, theres a TON of write ups on the PSW 110+, the amps are junk.. I ended up rebuilding the entire amplifier with quality components..

Thanks, any chance you have a link to one of the write-ups or guides to repairing these? I'm very new t troubleshhooting and reparing this kind of things.

The fuses came today. Tried one out just to check, and it blows immediately

[Bterrier]

Re: Polk Audio PSW111 Subwoofer - no power

There is a good chance the driver transistors are blown, those polk sub amps are notoriously underbuilt (especially older ones). There may also be conductive glue if it is older (brown glue that carbonizes and turns dark-brown/black and becomes conductive with time/heat). Polk also likes to use really cheap caps (crap like Jun-Fu, Fuhjyyu, etc.) in these amps that can fail as well. I'd start by testing the driver transistors (with a multi-meter/ transistor tester or just pull them and see if the fuse still blows) and also check the bias resistors and caps. If there is conductive (dark brown/black) glue scrape it off the board. If it is new enough to have a switching power supply that may have failed components as well.


Dayton (parts express house brand) and others sell replacement sub amps if all else fails, but at $50+ it probably isn't worth it (you can often find decent working subs on ebay for that price).


After owning a Polk powered sub (don't remember the exact model but it would have been circa 2005-2006 and failed in 2012) that blew its amp and an seeing what a steaming pile of crap the amp (cheap caps, conductive glue, undersized heat-sinks, etc.) was in a ~$300 sub (the Sony I replaced it with which was half the price has a much better built amp) I'll never buy another Polk sub/powered speaker (I could understand that build quality in a <$100 off-brand sub but not in something positioned as a "premium" product). Their un-powered speakers may be fine but I don't the trust the powered stuff.

Thanks, I'll definitely take a look at the transistors. This isn't too old, manufactured in 07 I believe. No brown glue, but they appear to be using some type of yellow foam or silicone maybe. There is one area where this yellow glue/silicone looks to have been heated up and turned brown. I'll upload a photo later.

[Khron]

Re: Polk Audio PSW111 Subwoofer - no power

That stuff turns brittle, conductive AND corrosive, so don't discount dissolved PCB traces or component legs either.