Powered subwoofer help please.

[ronnielee54]

My JBL PB10 powered sub started thumping the other day (similar to the way a radio will motorboat). Opened it up to examine circuit board, and it appears that one of the filter capacitors in the power supply section has a swollen top (not ruptured). Am wondering if this could cause deteriation in the value of the capacitor enough that the power supply is no longer outputting a true dc current which would in turn cause the amplifier to switch on and off every time the ac current goes negative. Comments please

 

[Vul Kuolun]

Quote:

Originally Posted by ronnielee54 /img/forum/go_quote.gif My JBL PB10 powered sub started thumping the other day (similar to the way a radio will motorboat). Opened it up to examine circuit board, and it appears that one of the filter capacitors in the power supply section has a swollen top (not ruptured). Am wondering if this could cause deteriation in the value of the capacitor enough that the power supply is no longer outputting a true dc current which would in turn cause the amplifier to switch on and off every time the ac current goes negative. Comments please

Chances are that the capacitor is dead.
Problem is, if you just replace it you still don't know the reason why it died. If you're unlucky (in fact you are, you're at least a man with a broken subwoofer

), the one you put into place instead blows up. Ugly.
I'd seek some help from someone familiar with Edison and stuff.
Good luck.

 

[tjohnusa]

If you are capable I believe there is a mod kit available for it from JBL I have a PB12 and found this while researching the sub I haven't had any problems....so far. This kit has resistors in addition to a couple of caps to replace.

 

[ronnielee54]

Well actually I am a little familiar with Edison and stuff. I have an Associates degree in Electronic Technology. I am a little rusty in the theory part of it because I never worked in the field of electronics on a daily basis. I had also pursued a degree in Drafting and design at the same time and was able to land a job with a Civil Engineering firm after graduation. Drafting pays better in my part of the country unless you want to work maintenance in a factory.
Anyway I think the reason the capacitor might have died is because the sub has no on off switch. The power supply part of the circuit is always on unless it is unplugged or switched on and off by a power conditioner. It has probably been on for 5 years or more without being shutoff except for power outages.

 

[Vul Kuolun]

Just kiddin'.
Tell me when you'll connect the sub the first time after the repair; i promise to keep my fingers crossed for you.