[sdiy] Dynacord Boomer Sampler PSU

[Dave Krooshof - dendriet.nl]

Hi y'all...


So I walked into this store, browsing for new gear, and came across a
weird box. It says "Dynacord Boomer Digital Sound Programmer". I asked
wat it was. They said all they knew was that it used eproms. They gave
it to me for free. Joy! It turned out to be a sampler.
http://www.synrise.de/images/dynacord-boomer.jpg

Although its specs are rather 1984 (8 bit/12kHz/1.3 seconds of
memory), I'd like to get it to work. It seems to be in good shape, but
the transformer is missing. So, now I need one or two transformers. I
traced the PSU board to figure out what I need. I got confused.

It uses  4 pins of a 8 pin DIN type plug:
http://pinouts.ru/connectors/din8cf.gif

pin 4&5 and 1&3 go to the two ~ terminals of a great (diode rectifier ring)
pin 2&8 go to the - terminal.
The elcos here are 16volts and 24volts max.
So far so good, but the odd thing is that the + is going to two 7805 ICs!

Pin 7 goes to 3 diodes.
diode one: goes via an elco to ground.
diode two:  goes to a 7815
diode three (in opposite direction) goes to a 7915
The elco's are 40volts max.
To me, this method of getting a symmetrical PSU is not familiar.

All 78xx/79xx share the 0 as ground. And just to be sure, I checked
that this 0 is the gound on the sound in/out terminals.


Does anybody know what type of transformer I need?
Or can anyone guess the voltages I need from this information?


BTW: The machine has an onboard UV lamp to erase the eprom memory! :-)
I'll look more healty with your help! ;-)

thanks,

Dave