Midi in not working

hi, my midi din in doesn’t work, is there something I have to modify or install after installing the image on the sd?
I tried inverting midi socket and the diode too but nothing work, I use the same schematic as my teensy interface and updated the resistor, 220 ohm before 6n138, 470 ohm between 6 and 8 pin of the 6n and 1k resistor from pin 7 to ground, do I missed something?

Hi, it works for me according to this scheme: 220 ohms, a diode, 220 Om is a midi input to the microcircuit. With a Raspberry pi diode, and a capacitor at +, 220 Om, the input is at + 3.3 volts,

You use also 220 ohm after the 6n138? And where goes the second diode please?

I can t read values on this schematic, seems that the files was compressed, I can t zoom in :frowning: thanks for help btw !

THe zynthian MIDI schematic . …


thanks but I only have 6n138 here :frowning:

It’s the pretty much the same thing . . .

I could just swap the opto and use same resistors values? sorry I m not a professional electronician! I learn all via git hub :frowning:

Yes. IT’s easy to get hung up on these differences but it’s going to work, unless of course there is something else wrong like a bad solder joint. The pin outs are the same . . .



it appears the 6n138 is actually an 8 pin device but it’s similar if you ignore pin 1 & 8 … .(if it has them, I don’t remember ever encountering one with 8 pins) Yes it’s that confused. :smiley:

thanks I ll check all this! I always control on breadboard before soldering! really thank you for your help!

do you know if there is something to edit to enable midi in? by exemple if I use custom wiring in the web conf where must I edit my wiring (midi input, output…)
sorry Zynthian is a bit confusing for me and I m lost between the blog, the GitHub, the discourse…



It’s just that the problem is with the details, so I’m doing what I’ll find out of. As the saying goes, I’m making out of shit and garbage.

sorry I don t understand what you mean?

@wyleu Are you sure the 6N139 is going to work just like that? The H11L1 has a schmitt-trigger after its receiver transistor, while 6N139 just has the “bare” phototransistor as its output. Also, looking at the schematic, it might work if you connect the 6N139 on pins (2,3) input, and (8,6,5) output side; that’s a different pinout though from the H11L1, so you wouldn’t be able to just pop it in place, ignoring two pins.

Dug this up because I’m finding myself in a similar situation for my potential 2nd Zythian :slight_smile:

I have to say I was thinking of deleting that post as I revisited it after a little bit of further reading. Apologies if it’s lead you astray. I’ve used the three opto set that was on the original allinone board on my machines that use 5 pin midi but I think the new boards do it differently.

I don t understand what you mean? Sorry