Eurorack module testing tool (DIY)


Wow, I cant believe this thing is working.
Sorry for my enthusiasm, this is my first time using a solder.

I am going to use it to play with banana modules,
my question is:

Is the tester using the switch pin in the front panel jacks ?
I want to use banana jacks instead the 3.5mm eurorack jacks.



no it’s not using the switch pin.


Just finished soldering the Module Tester. Heading to post office shortly, to pick up Ponoko case. Can’t wait to test the tester :slight_smile:

Random question: Has anyone encountered a Eurorack module which draws too much power to test with the Module Tester?


Just finished Module Tester! Took me a minute to figure out how to calibrate, but working perfectly now.

Awesome design.


Good job it worked or you’d need a module tester tester.



Anyone could be interrested on doing a small run for theses pcbs ?


A few notes on using the Ponoko case, based on my experience (YMMV):

1. Be careful with the outer diameter of your 20mm standoffs. They can interfere with case nuts and cause you to crack off the thin area that the case-screws go into. I always use Harwin brass/nickel standoffs from Mouser, and they were a tight fit here. I had to make sure that they were oriented a particular way, to give the nuts enough clearance.

2. I found it easiest to spray paint the case parts before removing them from the single piece of laser-cut acrylic. Tape off the cut areas, to ensure no bleed.

3. I know the BOM says 10mm standoffs, but I found that the Erthenvar jacks and 5K and 20K trimmers were tall enough that 12K worked better.


Hi all,

I got this all up and running — it’s fab! Wish I had it at the beginning of my project.

Everything works except…

I am having issues with the CV out — I just get a constant 10.8v output.

I also don’t appear to have any -12v output on the module power connector.



Checking the LM2990 — I don’t appear to have any power going in or out of it.

There’s no power at the input of D5 either.


Are you using an AC adapter?


Aha — that’ll teach me to blindly order a Mouser cart.

At least that was easy to debug—

Thank you — and thanks for this board — it’s brilliant!


A link to the BOM is on the tester page

Just scroll down a little.


Does anybody have Mouser BOM/Cart for tester ? If yes, could you please post a link


Hey guys, sorry for raising the dead…erm…resurrecting this thread again.
Just one question: are the outputs for testing simultaneous usable, or only one (selected) channel ? I don’t want to get puzzled by that fact if the tester is not working or the module :wink:


All outputs are running simultaneously.


You are my hero ! Back to work…


Just finished building two testers! I’m having word for word the exact same problem as @bkbirge described above. So just to clarify… the fix for the aforementioned issues is to replace the 20 Mhz crystal with something with a lower value?


No. Either you have the wrong parts or you didnt program it correctly, it has to be a 20 MHz part.


Understood! Thanks Altitude!