Behringer Ultrabass BX4500H schematic

[Soeren Poulsen]

I am in the process of repairing 2 of these bass-heads. I do not have the schematic, as You all might know, Behringer will not release their schematics.
Still, I have managed to get something from Captain Hook! - and I have been comparing a lot, handdrawing a lot, and looked a lot through a microscope.
Has other done similar, and shall we swap informations?
It seems, that 2 typical faults in this output board, is a bad through-hold connection on the 2 main e-caps, and the output transistors is not pressed enough to the heat-zink, by the 3 mm screws. I can still see, the stribes from the paintbrush, used for applying the heat-zink-compound.
In one of the 2 units, the transformer primary is 0 - 120 - 230 Volt ac.
There is opel loop between 0 and 120 Volt, but ok between 120 and 230 Volt.
I can start the powersupply by applying 120 Volt between 120 and 230 Volt wire.
That output amp is the Grounded Emittter type of amp, like Peavey also has made some of their amps.
Regards to all from Soeren Poulsen Denmark

[Steve L]

Behringer Schematics

Here are the preamp schematics.
I don't remember which power amp module is in that amp so I attached a few others.

Behringer BVT-4500H Ultrabass Preamp Schematics.pdf
Behringer LPA-1180 180W Power Amp Schematic.pdf
Behringer DPA400 (Rev.F) Digital Power Amp Schematic.pdf
Behringer BX-1200 Ultrabass (Rev.H) Schematics.pdf
Behringer BX-1800 Bass Amp Schematics.pdf

Steve

[Soeren Poulsen]

Behringer Ultrabass BX4500H schenatic / repair

Thank You so very mouch.
I have spend some hours, tracing schematics on the Internet, and now I have some 15 different schematics. Well, pressuer creates counterpressure!
I have taken a lot of photos of these amplifier boards, and it is writen P3000 on the board. It has 2 times 3 output transistors, 2SA1943 and 2SC5200, with MJE15032/33 as drivers. On the schematics I have found, the emitters of the drivers is connected to Gnd by each a 6,8 Ohm resistor, but this amp has an extra 6,8 Ohm resistor from the connectingpoint of the 2 emitter resistors of the drivers, and to Gnd.
Prior to this amp, I has been working on a Fender small pa amp, with the same type of output circuit. It took me hell of a time to get the schematic, and it turned out to be a Sunn amp, that Fender had sold under their brand. I do not have a homepage, to put it on, but if any is interested in the Fender SR6300P schematic, let me know, then I will send it to whoom want's it.
Regards Soeren Poulsen Denmark

[johnerbes]

Hello Soeren,
I am very interested in the BX4500H schematics that you have spent so much time creating, but when I try to open your attached file I only get a black screen. My BX4500H works fine, but I would like to modify it slightly by inserting a very steep 25Hz high pass filter (as recommended by Eminence) in the preamp stage to keep my Eminence Lab 12C driver from destroying itself in the 4.5 cubic foot vented enclosure I am building for it. Are those schematic files still linked to your post? If not, would it be possible to email them to me at jrerbes@att.net? Thank you so much. John Erbes

[Soeren Poulsen]

Hello John Erbes.
Well I do not have the schematic of the output amplifier in the Ultrabass BX4500. Someone attatched the pre-amp schematic, and it looks great, but the amplifier is the type, called "The tail wagging the dog", as my friend in Australia wrote.
Enzo has told us, that the output amp looks a great deal like the QSC 700 schematic, and I agree. If anyone want them, I have taken a lot of pictures of the Ultrabass BX4500 output module, so just ask for it, and I will mail them. I have attatched 3 for Your reference.
All best wishes to You all Soeren Poulsen Denmark

[diydidi]

Hi.
Can anybody repost schematics for BX4500H please?

[Jazz P Bass]

This is what I have.

BX4500h.zip

[diydidi]

Thanx Jazz.
BUT, the preamp schematic is totally different to the actual BX4500H.
Oh well. I'll keep searching.

[Jazz P Bass]

Well maybe the BX1200 preamp is closer to the BX400H.

Behringer bx1200 Ultrabass sch.zip

[Soeren Poulsen]

Hello friends. I have been given some schematics, and to my surprice, I found the schematic of the Behringer BX4500H bass guitar amplifier, output board, which is named P3000 on the board. When You look at the schematic, remember, that the mains transformer has one winding with center-tap for the pre-amp, approx 18-0-18 Volt, and a single winding, without centertap, for the power output. - a weird construction! I still have many more photos of the module, if any is interested. Just write me a mail. All best wishes to all Soeren Erik Poulsen Denmark
I am desperately trying to attatch the schematic 480KB, but the forum says, I have exceeded my maximum. Can anybody help me, by having the schematic, and uploading it?

[sugeda]

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