Is there something wrong with this poti circuit?

#1

Hi, I had really great time using my first axoloti this year, so when the last batch came out, I recommend to a great friend to buy one and start to build his own synth. But he is in a great trouble because his circuit didn't worked. It was his first soldering project so I was thinking about a bad solder join somewhere, I've redo all the circuit myself after I cleaned it up, nothing changed...

Here is a pictures of the circuit :

IMG_4303.JPG3869x2579 1.67 MB

Mounted like that :

BOB.jpg3508x2480 1.1 MB

All poti are 10k. I've tried with all VDD and GND. I'm 100% sure it's not the female hader on the board because I've tried all analog in individually with a breadboard and all worked finely. I've watched carefully if any wire touch another one, it's clean.

Maybe it's because he used this for wiring ? : http://www.e44.com/outillage/realisation-circuit-imprime/plaques-d-experimentations/lot-100-strap-en-bande-0.6mm-52mm-max-7.5a-jumper-JUMPER-100.html

Somebody have an idea to save my friend from his hard impatience ?
Cheers :slight_smile:

#2

Hello,

Check each potentiometer with a simple patch like this:

The reading on the display should be steady and range from 0 to 63.

If you're not getting any thing, do you have a multimeter? Check you're getting 3.3V between Vdda and GND on the pots. Check that you're getting a steady voltage that goes 0V to 3.3V on a potentiometer. Also make sure the Vdda and GND wires aren't touching - PA3 looks risky!

#3

Of course I did this simple test and this is why I can affirm that all analog in work perfectly when I try them with a simple poti on a breadboard. But when the circuit is on, all poti's are not working on the patcher. sometimes one of them, the other stay somewhere around 20 or sometimes at the maximum 64 or even around 0. Don't really understand what's happening.
But sadly I don't have any multimeter... Maybe it's time to buy one !

#4

Ok, disconnect all but one pot from the Axoloti, does that work? Then add each one in turn and test them individually.

#5

I did it, same problem, any poti works... Some of them are on 0, others around 20. I've trying this morning to change the vdd & gnd wire, or even changing their places in the circuit, nothing changed...

#6

Seems strange... They are all 10K pots? Not 1M!? In parallel, they will draw about 5mA from the Axoloti board which isn't a problem. It sounds like they're floating and not at any particular voltage which suggests the pots aren't getting 3.3V. A multimeter is needed!

I'm assuming those wires carrying GND and 3.3V are bare wire? Check they're not touching the metal on the casing pots.

#7

You have 15 pots in parallel, the current compsumption will be high, are you powering the Axo via USB or external PSU?
First try an external PSU, if still not working, disconnect one pot at a time to see how many pots you can use.
If you really want to use 15 pots try a higher pot value, like 100K, but it may have other problems because of the impedance of the Axo inputs.

#8

So, I think that idea with nude wire were not good. We probably made a short circuit somewhere, cause I've tested all potentiometer of the circuit with a multimeter, they was all totally dead. I've replaced them with 15 brand new, with normal wire, everything is working now. Thanks to all for your help, a multimeter was a great idea, now I have one !

I think it's probably because I've soldered my poti in the little hole and not in the 3 legs too. I've broke a brand new one by doing this. I didn't know that we can't do this...

Cheers :slight_smile:

#9

I'm interested to know how you got on.

I have a similar project and I'm just working my way through some troubleshooting.

Are you using modsource objects? I mention this because you have to set the maximum number in the patch preferences, that caught me out for a while.

#10

I've done 10 other projects with 10 other axoloti-core. So I've understood an Issue with the board, when you connect 15 poti's to the board, for exemple like me all 10k poti's, my problem was the push button I wanted to connect with them. I've plugged it into the Digital input "PC5". Doing this is terribly wrong, it's everytime affecting two potentiometer or sometimes more, I don't know why. So now I connect everytime the pushbutton to the PB8 and everything work well everytime.

If you did the same, keep this in mind. But for me a 15 10K potentiometer circuit work well everytime now.