16n Faderbank: build help, dev suggestions

[mlinton]

Ok so I’m trying to track the last channel that I’m having problems with to get it working (fader 9).

On the schematic I’m trying to trace the path to check the components but I’m not very experienced with Schematics. It would look to me that W8 is the component for fader 9. This would mean U6A and U6B, which based on the pinout looks like the left side of U6 (with Pin 1 at the top left). Here is a picture:

Which would also mean that the two resistors 43 and 44 would be involved:

Then channel 9 looks like it goes to Pin 23 of the CD74HC4067SM96 which is on the right side of the component pin second from the top.

Does this sound right? Is there a chance that the fader is bad too? What is the best way to test it?

[infovore]

@disc0p

It is all the channels though, so I guess it is the multiplexer?

Not necessarily. The mux has a VCC of 3.3V. If one of the voltage dividers is not set up right, it’ll send up to 5V into the mux, and when that happens, the excess voltage will lead to issues on all channels. I’ve solved “moving one fader affects all of them” issues by fixing the divider resistors on a single channel.

So: check all the resistors around the op-amps, and all the op-amp pins on the board. It could be a different channel flooding things.

[rondo]

Not sure if this deserves its own thread so I’ll just ask here: Has anyone tried building or altering the design of a 16n with 100mm long-throw faders?

I’m almost completely sold on building myself a 16n but I really like the physicality of 100mm faders. That’s the only thing holding me back.

[infovore]

Not that I know of, but - other than the change in almost all the mechanicals, it’s electronically entirely straightforward. Swap one fader part for a larger one.

[zoundsabar]

Hi all. Not sure of the best place to put this, but my 16n MIDI has failed to work, while the CV outs are still functioning. It was all working perfectly until I put it aside for a few weeks, and now the MIDI aspect is broken.

I’ve taken the top off the 16n. I used my voltmeter to look at CV out, which is in the range of 0 to approx 1.69 Volts on all the faders. The LED on the Teensy remains off when the USB cable is plugged in. I got a Sensel device which came with a working data micro USB cable, that’s what I’ve been using to test the 16n.

Is the voltage range on the CV outs correct? The github page says 0-5V.

I believe the Teensy is dead. I could try to unsolder it from the board and replace it. Is that a workable idea? Any other suggestions?

[Oootini]

Does it show up in the 16n web editor?

[zoundsabar]

Sadly, no. I tried that after it stopped working as a MIDI controller. The Teensyloader software doesn’t see it either.

[Oootini]

very odd. if there are no activty leds, and it’s not recoginzed by the loader, that sounds like it’s bricked to me…

[zoundsabar]

Thanks. I think I’ll try replacing the Teensy.

[infovore]

CV outs should be 0-5V; they get their power from the 5V pin on the Teensy.

But a Teensy shoulnd’t just fail after not having been used for a while. So my question is: is anything shorting it anywhere? A piece of metal or something on the back side of the case? A short might explain the voltage drop on the CV outs, and also why the Teensy isn’t even getting into booting.

[zoundsabar]

That was an excellent theory, but I looked on both sides of the board, and it appears clean and good, with no stray bits anywhere. I tried the 16n configuration tool in Google Chrome, but it doesn’t see the device. Also, still no LED on the Teensy.

Unsoldering the Teensy could be a pain, I’m not looking forward to trying that.

[jengineer]

Did you ever find a way to resolve this? I bought the same pre-populated Emitum pcb and I seem to be having the same problem. All the solder points look clean, and all the resistors appear to be correct, but my faders go from 4.5V at the top to around 1.5V 3/4 down, and then back to 4.5V at the bottom. And that’s just when they’re doing anything at all! Most of the time they’re completely unresponsive and I have to reboot the Teensy.

[AtoV]

Hi!

First post here! I’m Arthur, I’m the guy who did the redesign of the 16n known as the AtoVproject Rework or Berlin Modular edition.

Clients contacted me and asked me if some modifications could be to the firmware. The request was to add a MIDI Thru function where the midi data sent to the serial MIDI output.

I therefore got to work and implemented that and I pushed a Pull request to the main github. I think that’s a pretty useful function as it allows, for example, to add hardware control to a synth using the 16n while sending notes and clock to this same hardware from your DAW.

I tested it successfully on both 16n with Teensy 3.2 and Teensy LC.

I think it could be nice if that was merge to the master branch.

Let me know! Cheers

[infovore]

ahoy! I am probably the person to deal with that, and have been a bit snowed under with work, so the repo has languished a bit.

That seems like a reasonable request, especially if it’s behind a config option, which we could add to the editor. I’ve dropped some notes in the PR, but am happy to help get it through.

(Also - it’s a nice variant! I would adopt the power filtering going forward forever, tbh…)

[disc0p]

No, I couldn’t figure it out and got sidetracked. I bought cheap sliders and figured they were faulty, but I’m not sure at all what the issue could be or how to troubleshoot it.

[infovore]

I’ve seen a similar issue which I managed to solve elsewhere (@disc0p, @jengineer), on a board which had the wrong opamp chips on it. What are the opamps at the bottom of the board? (That is to say, the eight chips in a row). They should be MCP6004s.

The behaviour you’re describing, however, was similar to what I saw elsewhere, on a board populated with TL074 opamps, and it was a board supplied by Emitum, I believe.

If you’ve got a board with TL074s on: that is never going to work. They are the wrong part, and they’re not compatible. Speak to the people who made it.

[disc0p]

You’re right, they are TL074! Guess I will send Emitum a message and see what they say.

[infovore]

argh, that’s just infuriating, because that’s just straight up the wrong part. hope they can sort you out.

[disc0p]

They gave me a partial refund, hopefully I can swap them out for the right part, otherwise it will be junked I guess.

[infovore]

it is doable, depending on your level of SMD skill. the easiest way to remove the TL074s is to cut them at their legs (which will destroy them for future use, but they are cheap parts. This is a less good option with expensive ICs).

The body will drop free, and then with a soldering iron, you can carefully melt the solder and sweep up all the legs. Then, you can fit new MCP6004s like you’d fit any other SMD IC.

You might also be able to find somebody to assist here.