I think that with a little bit of effort, you could build the world's most ghetto MT-32. 😁

Just find a photo of the real new MT-32 as a guide, source the missing parts, apply a touch of heat and solder, and off you go.

That would be glorious.

so where does this go into? is it a pcb from a keyboard synth or something?

It was a set of two board. The second board is a E-20 control logic (keyboard controller, sequencer, arranger). The man who sold me it found these boards in a scrap and does not have any other parts or cables

I will try to identify power, MIDI IN and analog output and run MT-32 PCB. Since MIDI has no Opto-converter, the levels should be true TTL and I'm planning to use generic soundcard with Joystic/MIDI DB-15 connector which provides MIDI with TTL levels. The power should be +5V

A little doubt is a controller PROM. The original MT-32 has a display and some knobs on the face. Working inside E-20 this boars no need any controls and works "headless".

Unfortunately, I can't find a good photo of the "new" MT-32 PCB. The "old" PCB may be found there:

http://queststudios.com/smf/index.php?topic=1414.0

Can anyone provide a good photo of the "new/headphone" PCB of the MT-32 ?

The card was successfully revived. Thx to tnt23 !!

The missing parts were soldered back and viola! The card is working.

The main trouble was a LCD display with rare LCD controller SED1200, so tnt23
made a tiny "translator" with ATMEGA88 to the mainstream HD44780 command set.
This "translator" also donloads missing characters into HD44780 char generator.

Video:
http://www.youtube.com/watch?v=Pknr-oy8flI
(bad sound due to phone camera, sorry)

Photo set:
http://www.flickr.com/photos/46193097@N08/set … 57637506220566/

We are STRONGLY SEEKING for the original MT-32 case with original display and knobs,
perhaps with conpletely dead PCBs.

^ amazing!
please consider sharing that "translator" project, it could be useful in future repairs... 😀

keropi

http://sensi.org/~tnt23/sed1200emu/

^ awesome again, thanks!

The Roland E-10 keyboard contains this voice board too. It is revision 00 in my case, and has the same assy number as in these pictures. The socketed MT-32 ROM on this board says "2.0.0".
I hope to one day do the above project with my E-10. Not sure if my board is working though, that will be the first thing to check. I should compare it with my MT-32, both electronics and audio output. It looks to me like E-10 has the same synth board as E-20, but has a different CPU-board (left board/synth equal, middle board/cpu different, right board/power equal), based on the images referenced in this thread.

Image of the board found in my Roland E-10:

alec_v wrote on 2013-11-11, 20:06:

The missing parts were soldered back and viola! The card is working.

Some years ago, but I wonder how did you attach the MIDI port? By running a cable to the other board in the pictures, or on the same board?
What were the missing parts? I see an added 7805 VRM, a power plug, two pin headers, and a power plug, and the LCD parts. Anything else? Some small ICs in front of each midi ports on the back?
Anyone that knows something or want to guess is welcome to answer 😀

perhenden wrote on 2021-12-09, 19:56:

Some years ago, but I wonder how did you attach the MIDI port? By running a cable to the other board in the pictures, or on the same board?

First runs were done via onboard connector with TTL MIDI signals. The said pin connector used to be attached to another epiano control board sending MIDI flow.

What were the missing parts? I see an added 7805 VRM, a power plug, two pin headers, and a power plug, and the LCD parts. Anything else? Some small ICs in front of each midi ports on the back?

7805 voltage regulator, yes. This one gets rather hot, because in MT-32 it is mounted on the metal case for heat dissipation. I failed to source proper power switch so just soldered a wire jumper in place to always have the board powered.
Then DIN-5 MIDI connector and optocoupler, for external MIDI source.
Then a couple of TRS 1/4" jacks and op-amps with other components, for sound output.

MT-32 Service Manual was of great help, showing both schematic and PCB connections in great detail. So it was just a matter of finding the missing part on the schematic and installing it on the PCB.