Behringer Ultrabass BX4410 (or any Behringer amp with the same output section)

[flyingdutchman]

Another chapter in the Book of Tough Nuts, this power amp section has a rather particular configuration (floating power supply, output devices have collectors connected to Gnd). The configuration isn't the problem, the way this amp is laid out and the particular fault I'm dealing with are.

I would be grateful to anyone who could provide a schematic of this amp, or for that matter, just. the power amp section which goes by the name of P3000 and most likely is used in other Behringer products as well.

[Jazz P Bass]

That 'flying rail' design is commonly used by Peavey, QSC & Crown.
Try this QSC schematic.
In may get you in the ball park.
Link: QSC USA400 Service Manual free download,schematics,datasheets,eeprom bins,pcb,repair info for test equipment and electronics
And this post has a nice explanation of the design, specifically post #22.
http://music-electronics-forum.com/t34497/

[flyingdutchman]

I am quite familiar with the "flying rail" type of output stages, and I indeed have the QSC schematic you've mentioned.
(Last time I looked, QSC had schematics of all their older equipment available from their web site)

My problem is not with this type of output stage per sé, but with Behringer's way of implementing it . "Opaque" is putting it mildly. It's a real bastard to work on.

[Jazz P Bass]

Just trying to help, mate.
Behringer equipment sucks to work on.
Period.

[flyingdutchman]

Behringer equipment sucks to work on.

You're telling me

[flyingdutchman]

Nailed!

The attached schematic has been useful in resolving the problem. The output section is not identical, but fairly close.

[Jazz P Bass]

Got it saved.
Thanks.