Powered subwoofers

[glockstr]

I have a collected couple of powered subwoofers in the garage over the years. Just couldn't make myself throw them away and always planned to fix them. I started that this past weekend and noticed both have the same problem or seem to.

They both power on, red light when plugged in and green light when turned on. I suspect the input is working because the auto on trips the green light when a signal is fed from the receiver and I hear the relay click on. I know the receiver's sub line out is good. No fuses are blowing and nothing get's excessively hot, just warm. I get no sound from the speaker, no bumps pops or hums, just silent. I read many of the posts here and they all refer to hums or pops but I didn't see anything with my symptoms. No components look burned or appear to be leaking. Any suggestions on what to try would be appreciated.

Thanks,
glockstr

[999999999]

Re: Powered subwoofers

First, supplying good top-down and bottom-up (not angled) pictures may help, and if you can find a schematic that would help too.

Generally speaking you would trace and measure the signal path and power path. While you do have some portion getting power it isn't necessarily proof that all the power subcircuits are working. Often there are at least 3 separate supply sections including high(er) voltage positive and negative rails for the power amplification stage, lower voltage positive and negative rails for an opamp or equivalent input stage, and at least a single rail of lower voltage still for logic ICs or circuitry.

A quick couple tests I would do with regards to these is trace back the speaker output path to the last IC or transistor before it, and measure whether the appropriate pins have supply voltage and audio signal. That last IC or transistor is a frequent failure point so if there's power and signal without output, AND you don't have a protection circuit fault or stuck relay, then it's probably a bad transistor or IC.

[budm]

Re: Powered subwoofers

Makes and Models?

[glockstr]

Re: Powered subwoofers

Thanks for the advice. I don't think I will be able to get a hold of the schematics as the subs are fairly old. They are a BIC V80 and an Aiwa TS-w35U. I will write the companies and see what they say. Anyway backtracking from the speaker wires shouldn't be too bad. There is plenty of room on the boards and not much surface mount stuff.

*edit* Oops, spoke too soon. Found the Aiwa schematic under the model number tsw37 here;
http:// (insert www here) .eserviceinfo.com/index.php?what=search2