MIDI in trouble [basically solved]

Discontinued DIY products Shruthi
#1

Hi, all. First, thanks for the valuable threads here that have already solved some of the issues I have had with my Шрути-1. But I remain rather stumped by my MIDI in troubles, and I haven’t found a thread that matches my issues.

MIDI out works–I did the backup/SysEx dump to my interface (NI Audio Kontrol 1) and the MIDI IN LED on the interface flipped out.

For the MIDI keyboard, I’m using a Korg microKONTROL, plugged into the wall (when plugged into USB, its MIDI out works exclusively as a MIDI-USB bridge). I don’t have easy acces to another device w/ MIDI out (except the Audio Kontrol 1, but I’m not sure if it can send MIDI signals out! I could get it to behave like a MIDI keyboard in my DAW, but that was via NI’s software). So here’s one potential stumbling point.

On the control board, the 6N137 behaves like this:

Pin 2 gets 0v but is connected to D1 and R19, through to MIDI in’s pin 4
Pin 3 gets 0v but is connected to D1 and MIDI in’s pin 5
Pin 5 gets 0v and goes to GND
Pin 6 gets 4.89v and is connected to R14 and pin 14 on the ATMEGA. When I jiggle pitchbend on the Korg, the voltage drops to around 4.7v or so.
Pin 7 gets 4.85v
Pin 8 gets 4.87v and is connected to C1, a 220 resistor, and R14

In other words, it looks like it should all be working, as the optocoupler does react to MIDI signals. But I don’t get the little note icon on the LCD (or pitchbend or anything else; I’m not even sure I know what they look like!), and, rather obviously, I get no audio out (though I do via the S1 trigger). I did these tests with the device on MIDI channel 0 and the Korg on channel 1, but even with the device on channel 1, I get no note icon.

Any ideas where to go from here?

#2

They should both be on the same channel :slight_smile:
You need to play notes before the note icon appears and it usually dissapears rather quickly…

#3

First, set Shruthis MIDI receive channel to 0 which is omni mode to rule out all possible Channel mismatching problems.

#4

It is set on 0. I also tried it on 1, but I saved the default to 0.

#5

Did you measure for continuity on all the connection you describe?

#6

Yes, what I meant above when I wrote “connected” was that my multimeter beeps when I do continuity tests between the optocoupler and the other components.

#7

Maybe try it with the NI to the midi in or with an other midi cable.

#8

Do you get somethink like a soft synth working on your computer with the korg via a midi cable to the NI?

#9

it’s not easy to say when you can’t be sure about your midi source. since everything else at leat looks fine, maybe just try to get hands on a midi keyboard to try. haha go to your local music store and say you need a midi keyboard but want to try if it works with your portable synth.
other than that, since you seem to need midi obviously, there’s good chances you can still grab a GM5 or GM5x5x5 board at midibox.org. those are reliable USB-MIDI interfaces almost for free (15-25€ overall material cost depending from 1x or 5x in/out)

#10

If you need a gm5 chip and single pcb 1 I/O (though you can add 4 more I/Os with a proto board) PM me.

#11

Thanks for the suggestions!

A breakthrough, and I finally see the note icon!

I created an “external midi” track in Logic, drew a pattern on the piano roll, and was able to send it to the Shruthi-1 via the NI, so:

Mac(Logic) -usb-> NI -midi -> Shruthi-1 (-audio-> amp)

works! Which means that:

Korg -usb-> Mac(Logic) -usb-> NI -midi -> Shruthi-1 (-audio-> amp)

also works! I can play the Shruthi-1 with the Korg. I only need two other devices in the chain, with one running costly software (I couldn’t get this setup to work in Live.)

This also works:

Korg -midi-> NI -usb-> Mac(Logic) (-audio-> amp)

to play a soft synth (I also couldn’t get it to work in Live), so it proves that MIDI out on the Korg works.

Yet Korg -midi-> Shruthi-1 (-audio-> amp) gives me nothing.

While searching this issue before posting, I saw that others had written that they had some keyboards that simply didn’t work with the Shruthi-1 for some reason. Maybe we should make a list of those keyboards and tentatively add the microKONTROL to it?

Needless to say, I think I can safely consider my Shruthi-1 FULLY FUNCTIONAL. Hooray!

#12

I bought a microkontrol a few weeks ago… It works fine with my Ambika and anushri… Didn’t test it on a Shruthi yet but I don’t think it’s different…

#13

Today I decided to see if this would work:

Mac(Logic) -usb-> Korg -midi-> Shruthi-1 (-audio-> amp)

and, well, it didn’t at first. Then I kicked the cable in disgust, and the synth sprung to life. So with the MIDI cable precariously bent and working, I shut both devices off, carefully removed the usb from the Korg, and, well…

IT WAS THE MIDI CABLE’S FAULT!

Such a pleasure when the fix is so easy. The cable is literally brand new–I bought it only once the Shruthi-1 was complete, as a sort of present to myself for building a functional unit. Alas, it’s flaky, so I might just chop the heads off and resolder new ones on.

#14

And that is the only way to cope with cables :wink:
Soldering them by one self saves money AND nerves…because time (for troubleshooting) is money, mostly not recognized - incognito !

#15

Right. And it’s especially annoying since I had done continuity tests on the cable itself, etc., etc…

#16

Yeah, but the problem with those mostly molded connectors is, that nobody could take a look inside. And so surprises are on the program, hehe…

#17

Right. Anyway, everything is super functional, and I made use of the nerdy section of the manual to map the 8 encoders and 8 sliders of the microKONTROL to 16 diff parameters on the synth, and then I infuriated my neighbors.

Have no idea to what I should map the pads, other than maybe the trigger notes…