Eurorack module testing tool (DIY)


when I open the eagle file for this, it says board & schematic are not consistent, now i’ve got the fear about starting my build, i’ve started populating from the board markings but I haven’t soldered anything yet



I am using the tester these days, it’s working like a charm, but
I have a simple doubt due my noobness.

Are these “steps” in the AUDIO OUT mode a normal behaviour ?


(Sorry for the low quality picture, ipad camera here)


Yes, the audio output is generated at 39kHz, so there are steps between samples - there is no steep reconstruction filter to get rid of them, just one or two poles. Each step should be about 25µs wide.


Great, I was thinking I did something wrong.
Thanks, really useful machine.


My module tester functions properly but the voltage regulators get really hot and it’s just killed a second psu.
the psu was 12v AC 1A
can anyone point me in the right direction of what might be wrong?


you have a power rail short


if there was a power short surely the module tester wouldn’t power up ?


does anyone have a link for a decent 12v 1A psu in the UK?


>if there was a power short surely the module tester wouldn’t power up ?

It would if it was on the -12V rail.


ok, thanks for the help altitude :slight_smile:


I had a backwards diode, there may be a short as well, still getting a single beep testing continuity between -12v and ground


Hello; I’m looking for a little assistance with my build.

Before I describe my problem, I just want to say how beautiful this thing is. I really enjoyed the experience of putting it together and am sincerely appreciative of the art that went into the layout of the components.

Ok. Here is where I’m at:

> the device boots and seems happy
> all of the measurement seems to work for the inputs (gate in and audio in)
> clock out and gate out work splendidly
> CV OUT and AUDIO OUT are not sending any signal (verified by patching to both audio in and the CV input of an other oscillator)
> +12 supply out reads 11.42V and the +5 reads 5.005V
> -12 power supply output reads .245V (!)

I’ve been checking things to find the power supply problem and have yet to find the issue. I’m pretty new at the circuit-debugging (and am actually looking for someone in LA to give me a few lessons) - so any tips would be appreciated.




Check for a short between the -12V supply and ground. If there is one, try removing all socketed ICs.


Thanks; I’ve been investigating down that path. I have found that the voltage going into the 2990T-12 (IC10) is off: -1.137. Something upstream of that puppy is jacked. I’m off to work and then back this evening for more investigation. Cheers!


You are using an AC/AC power supply (you didn’t say …) ?
An AC/DC power supply would not work …


Used this one:

RockBirds New DC 12V 1A Switching Power Supply Adapter For 100V- 240V AC 50/60Hz Black


Your power supply adapter is the problem! You need an AC to AC adapter.
Something like this would work.


Yes, you need an adapter with AC output.

If it’s not bulky, you can be sure it’s the wrong kind of adapter :slight_smile:


Well, that is an easy fix then - no soldering required :slight_smile:

The AC/DC power supply should not have killed anything, so you just need to wait for that AC/AC power supply to arrive …


I’m mortified.

It is not like that little detail isn’t a) bolded in the instructions, b) clearly marked on the diagrams and circuit board itself, and c) referenced helpfully above to others who have had the same problem. I swear that I read the thread several times before I was brave enough to post. This is worse than when I spend twenty minutes looking for my glasses … only to find them on my face. Sigh.

Sincere apologies for wasting anyones time with this (esp. Olivier). And, thanks again for the help