realizing this may not be the right forum, but hoping an electronics whiz can help a brother out...
I have a Polk DSW1000 subwoofer w/ a built-in amp. The amp powers on OK, but will not start producing sound until after it has warmed up for anywhere between 10 and 30 minutes. After that time, it is not unusual for it to kick in for a second, then kick out, then kick in for 2 seconds, kick off, etc until it finally outputs sound continually, and then it will work OK until I power it off & let it cool down. Re-powering starts the process over again.
To my fairly novice mind, this seems like it might be a capacitor, so I pulled it apart today to look for any obviously bad (i.e. leaking) capacitors. I did not find any, but I did find two that have their tops swollen, and I wonder if they might be it..
Does anyone know the best way to troubleshoot those? I can de-solder them & put in new ones if I need to, but hoping there was maybe some way to test them while they are still in the unit?
Or, does it sound like I am off on my diagnosis, and maybe it's something else? Any suggestions on where to start looking? I can use a meter, but am not super versed on electronics. If I could find a shop to send it to, I would, but I can't find any shops that will work on it for some reason.
Thank you so much for any replies! I am attaching some pics of the two suspect caps...
I have a Polk DSW1000 subwoofer w/ a built-in amp. The amp powers on OK, but will not start producing sound until after it has warmed up for anywhere between 10 and 30 minutes. After that time, it is not unusual for it to kick in for a second, then kick out, then kick in for 2 seconds, kick off, etc until it finally outputs sound continually, and then it will work OK until I power it off & let it cool down. Re-powering starts the process over again.
To my fairly novice mind, this seems like it might be a capacitor, so I pulled it apart today to look for any obviously bad (i.e. leaking) capacitors. I did not find any, but I did find two that have their tops swollen, and I wonder if they might be it..
Does anyone know the best way to troubleshoot those? I can de-solder them & put in new ones if I need to, but hoping there was maybe some way to test them while they are still in the unit?
Or, does it sound like I am off on my diagnosis, and maybe it's something else? Any suggestions on where to start looking? I can use a meter, but am not super versed on electronics. If I could find a shop to send it to, I would, but I can't find any shops that will work on it for some reason.
Thank you so much for any replies! I am attaching some pics of the two suspect caps...
Attachments
You can pull your capacitors and test with this $94 ESR meter: https://www.newark.com/peak/72-1283...-22000mf/dp/56Y1286?searchref=searchlookahead
Or you can replace them for about $.40 each.
You are obviously missing some. These switcher supplies have a 200 v capacitor somewhere near the incoming AC power. Right after the rectifier.
This import switcher garbage is rather unrewarding when it comes to repair, is why noone will bid the job. I wouldn't mind spending $1 on it but your chances of success are low. Have you found a schematic diagram? You could also have a bad solder joint that connects when the board heats up. Good luck finding it. Pressing joints with a wood stick is one way, to see if it got better, but intensely dangerous with 120 vac running around. Wear safety glasses and don't work alone. Don't touch anything with 2 hands. 25 v across your heart can stop it. Don't wear jewelry on hands, wrists, or neck. 1 v through a ring at high current can burn your flesh to charcoal.
Or you can replace them for about $.40 each.
You are obviously missing some. These switcher supplies have a 200 v capacitor somewhere near the incoming AC power. Right after the rectifier.
This import switcher garbage is rather unrewarding when it comes to repair, is why noone will bid the job. I wouldn't mind spending $1 on it but your chances of success are low. Have you found a schematic diagram? You could also have a bad solder joint that connects when the board heats up. Good luck finding it. Pressing joints with a wood stick is one way, to see if it got better, but intensely dangerous with 120 vac running around. Wear safety glasses and don't work alone. Don't touch anything with 2 hands. 25 v across your heart can stop it. Don't wear jewelry on hands, wrists, or neck. 1 v through a ring at high current can burn your flesh to charcoal.
Those bulges are definitely bad.
How old is the unit? Might it perhaps be from the badcaps era? badcaps.net
How old is the unit? Might it perhaps be from the badcaps era? badcaps.net
Gents: Thank you so much for your replies - I replaced the two caps in question (and tested the (3) 200v, 1000uf caps that you reference, @indianajo, though they tested good). It does start reproducing sound immediately now! (yay!!) BUT... when I turn it off now, it makes a loud pop (like the sub gets a jolt) Any ideas what that might be? (it didn't do that before...)
Bing seems unable to find a schematic diagram of a Polk DSW1000 . There were several questions asking for one that it found.
There are amplifiers with elaborate protections to prevent noise during power up and power down. Considering the price of Polk products, I rather doubt that this feature is included. Live with it or trade up.
I picked up a used amp with such protection this month for $106 +tax+freight: a QSC CX302. Suggest you search for a schematic diagram on any product to plan to buy, before you buy it. You can analyze that diagram or manual for what protections it offers before purchase. CX302 also shuts down the power supply if DC voltage appears at the speaker terminal. Highly useful if your speaker costs more than the amp. Mine does. Some amps shut down if the heat sink temperature exceeds a certain value. Also useful. Some amps have a "VI limiter" that limits the current out to the speaker port. Some early amps had a speaker fuse, which by experience proved to be tragically useless to prevent either amp or speaker damage.
There are amplifiers with elaborate protections to prevent noise during power up and power down. Considering the price of Polk products, I rather doubt that this feature is included. Live with it or trade up.
I picked up a used amp with such protection this month for $106 +tax+freight: a QSC CX302. Suggest you search for a schematic diagram on any product to plan to buy, before you buy it. You can analyze that diagram or manual for what protections it offers before purchase. CX302 also shuts down the power supply if DC voltage appears at the speaker terminal. Highly useful if your speaker costs more than the amp. Mine does. Some amps shut down if the heat sink temperature exceeds a certain value. Also useful. Some amps have a "VI limiter" that limits the current out to the speaker port. Some early amps had a speaker fuse, which by experience proved to be tragically useless to prevent either amp or speaker damage.