VOGONS


First post, by alec_v

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I've bought a Roland E-20 Voice Board at local flea market in good condition.

Surprisingly, it contains labels: MT-32 and MT-100. It seems it's just a MT-32 (new/headphone version) board w/o analog connectors, MIDI connectors and optrons and power supply parts.

d38c001c7c11t.jpg

Is it possible to upgrade it to the MT-32 ?

Reply 1 of 9, by SquallStrife

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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.

VogonsDrivers.com | Link | News Thread

Reply 2 of 9, by keropi

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

🎵 🎧 PCMIDI MPU , Orpheus Soundcard , Action Rewind and Megacard website

💻 WTB Amstrad PC7486SLC-33

Reply 3 of 9, by alec_v

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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

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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 ?

Reply 4 of 9, by alec_v

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The card was successfully revived. Thx to tnt23 !!
10773754834_c6a435912a_z.jpg
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.

Reply 5 of 9, by keropi

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

🎵 🎧 PCMIDI MPU , Orpheus Soundcard , Action Rewind and Megacard website

💻 WTB Amstrad PC7486SLC-33

Reply 8 of 9, by perhenden

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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:

DSC_0910_2.JPG
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Reply 9 of 9, by perhenden

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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 😀