Using dsp module from Behringer MX1804X

Hi,

i want to use the dsp fx module(“DPM1”) i harvested out of a MX1804X behringer mixer. (to prove to myself that i can and get a cheapass fx module)
thats why i want to find out the pinout of that thing.
i googled a lot but did not find a working download for the service manual.
any idea where to get that?

is there a way of finding out the pinout on my own? its a 10 wire ribbon cable.
the module has its own 7805 regulator (i guess to make 5v for the dsp processor) so i guess it gets only +/- 15v from the mixer psu and generates the 5v from the positive rail.
it also has its own controlls so i guess there is only voltage rails and audio i/o on the connector.
i guess it should have at least mono in and stereo out, gnd, + and - voltage. the other pins are probably all ground or nc i guess.

i would now first messure the connector on the mixer to find which pins have the power rails, then just try to connect an audio signal to the other pins and check which pins have an output.
is that a good idea?

how do i find out the right levels?
i guess once i know them i can scale them using opamps but until then is it likely i will break something when testing with line levels?

I think the easiest way to find out the pin in and out without documentation is from looking at the board of the mixer you took it out.

I think you can download the service manual here:
http://elektrotanya.com/behringer_mx1804x.pdf/download.html

I’ve used the above site to download an sp-202 service manual, so that pdf should be the real thing…

the elektrotanya and some other sites from google did not works.

thanks a lot to ByteFrenzy who sent me the file.

Yeah, searching for tech docs can be very frustrating. Lots of sites that promise the schematics and the service manual and only have the user manual and quick start guide or some youtoob review by a guy named tom, dick or harry.

@loderbast: Sure it works - you might have to deactivate your adblocker. That worked for me.

Got that DPM1 working…

I take the manual from the mx1804. With a bit reading & trying, you can find the pinout for the ribbon cable (x4 is the connector). Works fine but you need maybe a little bit of preamping because the DPM1 wants high level input (I measured 13.6V sine Vpp when the clipping led came on). Actually to put it into a modular, so I went on 7 times gain inwards and attenuated by 10 times on the output.

That little guy seems to have midi input, its maybe worth trying it, I found no technical information for this. D/A A/D is CS4220 from cirrus, which is maybe not the most bad one.

Out:
1: red line, Input 1
2: Input 2 (added with In 1 via 100k sum)
3: Analog GND
4: Output L , keep care , it is directly from an TL074 derivate out, no protecting resistors
5: Output R, same with left out
6: +12V
7: GND
8: -12V
9: Digital GND
10: +10VDC (i got them by putting diodes to +12V , 4 pieces if they do 0.5V each)