VerticalTwist MIDI/Sampler Econet Interface Pinout

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hoji
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VerticalTwist MIDI/Sampler Econet Interface Pinout

Post by hoji » Fri Nov 01, 2019 4:12 pm

Part of my excitement about finding the A5000 was fond memories of using it as a MIDI tracker at school; to that end I picked up a VerticalTwist MIDI / sampler econet interface complete with software and manuals (if anyone needs them let me know, if that's even legal?!) initially hoping to play some stuff through my old Yamaha MU-50 synth, then getting a bit more involved.

It appears from reading the sampler manual that there's a breakout cable for the econet DIN interface providing MIDI in, MIDI out and a mono jack for the sampler - but I can't find any reference to it, nor the pinout of the connector, anywhere. Does anybody know what this pinout might be? If I do find it, or work it out, I'll update this thread for posterity...

I'm also looking for a copy of !WIMPTracker, as for whatever reason the version installed on my machine throws an exception when started.
Last edited by hoji on Wed Nov 06, 2019 5:49 pm, edited 3 times in total.

philpem
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Re: VerticalTwist MIDI/Sampler Econet Interface Pinout?

Post by philpem » Sat Nov 02, 2019 10:49 pm

Is that the one which was on ebay the other day?
If so - glad it went to a good home!

If you can provide high enough resolution images of the PCB (both sides), it might be possible to figure out the pinout by following the tracks. That of course assumes they don't dive straight under a chip or something...

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hoji
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Re: VerticalTwist MIDI/Sampler Econet Interface Pinout?

Post by hoji » Sun Nov 03, 2019 10:19 am

Haha indeed it was Phil! Yes, no unused hardware in this computer lair. My thoughts exactly regarding figuring out the pinout. I'm describing PL1 from right to left in the photo, pin 1 to pin 6 (EDIT: actually 1 to 5!) , as this corresponds to the DIN connector pinout.
midi1.jpg
PL1 Pin 5, ECLK*: Transistor TR1 is driven by pin 6 of the STM transceiver, TR1 then pulls a resistor low, and this is connected to pin 1. Midi out?
PL1 Pin 4, ECLK: This is connected to the +ve input of the optoisolator (pin 3), which is connected to pin 2 of the STM transceiver... so Midi in?
PL1 Pin 3: Ground
PL1 Pin 2, EDAT: This is connected to the -ve input of the optoisolator (pin 2). No idea... is MIDI In differential, and MIDI out ground referenced?
PL1 Pin 1, EDAT*: AC coupled to ground via C6 and loaded down with a resistor, then coupled to the base (edit, cathode!!) of TR2 (used as a cathode follower buffer?), so Sampler in?
midi2.jpg
Last edited by hoji on Sun Nov 03, 2019 2:37 pm, edited 1 time in total.

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IanS
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Re: VerticalTwist MIDI/Sampler Econet Interface Pinout?

Post by IanS » Sun Nov 03, 2019 10:42 am

I also have one of these (without the cable), so would be interested in the software.

MIDI is a 5mA current loop, and the input is normally opto-isolated. See the examples - https://learn.sparkfun.com/tutorials/mi ... ementation

So I traced my board, and this is what I worked out.
3- GND
2 & 4 Midi-in, they only connect to the opto-isolater (6n138)
5 is via TR1 and a resistor to Pin 6 (TX) of the seiral chip, so this will be Midi-out. There may have been a resistor in the cable to ground for the other pin.
1 goes via TR2 to the A-to-D converter so will be sampler in.

Edited: changed numbering to match yours, and match the Econet module pinout. Pin 5 is nearest the short PCB edge.

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hoji
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Re: VerticalTwist MIDI/Sampler Econet Interface Pinout?

Post by hoji » Sun Nov 03, 2019 2:37 pm

Bien sur IanS, send me a PM (I've not been here long enough to initiate) and I'll email the floppy images across to you.

Your explanation makes perfect sense; I imagine there will be a ~100ohm load provided by the optoisolator-resistor in the device connected to midi-out, so perhaps an extra resistor is not required? I'll put one in initially for safety during testing certainly.

Time to find some old cables and chop 'em up... I'll be back :)

EDIT: You got mail!

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hoji
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Re: VerticalTwist MIDI/Sampler Econet Interface Pinout?

Post by hoji » Sun Nov 03, 2019 4:42 pm

Great success! Our track-following was correct; the loopback adapter is as follows (DIN numbering)
loopcon.jpg
1 -> Sampler in
4 -> 3, MIDI-OUT to MIDI-IN+
5 -> 2, MIDI-IN- to GND

MIDI-IN has a 220ohm current limiting resistor for the opto, so all was well using a jumper.

!MIDItest2 reports all is well. Awesome.
looptest.jpg

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Re: VerticalTwist MIDI/Sampler Econet Interface Pinout

Post by IanS » Tue Nov 05, 2019 7:24 pm

My hardware also passes the self-test, which is good.

hoji was kind enough to send me a copy of the software, which I've attached here.

(I have an alternative reason for posting the software, one of the applications cause the PS/2 to Arc keyboard adapter to crash, which is odd)
Attachments
VTmidi.zip
(493.83 KiB) Downloaded 2 times

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hoji
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Re: VerticalTwist MIDI/Sampler Econet Interface Pinout

Post by hoji » Fri Nov 08, 2019 11:05 am

Excellent news Ian - how odd with the PS/2 adapter. I intend to get one of those at some point in the near future so we'll see how that goes.

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