Definitive Technology BP7006 AMP Guide Help

[Brucetafer]

Hey guys, Trying to make a write up with DEF TECH to help people keep these amazing speakers working.. Theres a bunch of people needing help and wanted your alls amazing input on why they go bad since they are still being made.

These amps are for the powered SUB only, and have no input for the rest of the speakers in the tower. The units power on, but have no output to the speaker, then after 20 seconds or so they start a low humming sound 60-80hz... if anybody has any input, Im going to completely destroy one of these amps trying to figure out the issues..

Thanks again!

[CapLeaker]

Re: Definitive Technology BP7006 AMP Guide Help

as usual, always start with checking all the voltage rails and the output transistors.

[Brucetafer]

Re: Definitive Technology BP7006 AMP Guide Help

Checked everything, all came with 67.2v on all rails. output trans look good.

[momaka]

Re: Definitive Technology BP7006 AMP Guide Help

Hmm... let's see: G-Luxon caps and crap tan glue (that probably hasn't turned brown and conductive yet).

I'd start with the G-luxon electrolytic caps. If you don't have a cheap ESR meter (like those sub $10 ones on eBay and AliExp.), now would be a good time to get one. Then pull them and out see if they still show good capacitance and ESR or not. Or just replace all of the caps, including the big ones... but that would be expensive and wouldn't give insight as to whether they were part of the problem or not (as there is a chance there may be more than one problem.)

Case in point: I worked on an old JBL plate amp last year with similar symptomps: one channel buzzed quite a bit (though the amp actually still worked... just very poorly). It used a classic linear (line-powered transformer) PSU like yours and one of the big filter caps was open circuit. Replaced that and got the amp working again.

On a second note, does this amp have analog input only? If yes, perhaps it's also worth checking if the input connector(s) for damage. An open input can make the amp buzz and "do nothing" too. In fact, I see what is possibly "speaker-level" inputs with some resistor droppers(?). If that's the case, those could be open/damaged and causing the "no sound" too.