Eurorack module testing tool (DIY)


parts should arrive in the next few days.

apart for all the all the ICs and LCD is there anything else i should be looking at considering i shorted the 12v line across the 5v line?

The power supply appears to be distributing the correct voltages in the right places.


I built a tester recently and soldered the diode that flies over the 7805 backwards - in effect bypassing it. This pushed 14V or so to the MCU and the LCD. MCU was fine, LCD blew up.


hmm. cheers. LCD is definitely gone screwy, but i suspect my MCU is gone too - button presses register only once on power up and then go unresponsive.


@ootini: A suggestion-you could try implementing a modified version of the Blacet module input protection scheme by replacing D8 by a big 5V1 zener (or even better, piggybacking it on top of D8), then cutting the 5V line going to the Euro header and bridging it with one of these. Any 12V flowback will be clamped by the zener and trip the polyfuse.


thanks gwaidan. yes i guess i will have to consider something like that. i think i’ll use a power cable that doesn’t expose the 5v line, that might be easier. i could always swap out the cable for a full cable if i needed the 5 volt line.


I know this is an off topic question but I’m already looking to start modding this piece. I don’t have a solid panel for it so of course I’m just sitting it on plastic spacers for now. This means the LCD is always laying flat and difficult to see, so I’ve pigtailed it and housed it in a plastic case which sits it at a 33 degree angle, my real question is, can this be tuned for hertz to volts, through code or pot adjustments. You see I really wanted to use this to tune other stuff than just eurorack?


> can this be tuned for hertz to volts, through code or pot adjustments

Possible with a firmware mode, but the result would be crappy since the 12-bit converter used is not very accurate for V/Hz.


Yes, I should’ve seen that.


this look ok to burn the firmware on the 644? do i need to add a lock step after the module_tester.hex?

avrdude -B 100 -V -p m644p -c avrispmkII -P usb -e -u -U efuse:w:0xfd:m -U hfuse:w:0xd4:m -U lfuse:w:0xff:m

avrdude -B 1 -V -p m644pp -c avrispmkII -P usb -U flash:w:module_tester.hex:i -U lock:w:0x2f:m


yup, that’s what I used (today actually)…


great. thanks. burning tonight hopefully.


ok all burned without a hitch.

calibration, case, and then combing the art of electronics book gathering dust on my shelf to look for cool circuits to build.


yay! another new AVR’r proving it’s easy :slight_smile: AVR-ISP mkII coming with my next order of stuff.


has anyone set theirs up for powering MOTM or Blacet/Paia modules during alignment?


calibration. i should be on 0-5v for the cv out yeah?


Calibrate with 2 oct arp, aim at +1.000V and +3.000V


Hey guys,

so Im ordering my bom on mouser and found the 863-MC74HC165AN obsolete

wondering if this other will do… I double checked datasheet and seems fine to me



Yes it works.


Cheers pichenettes!

here is the mouser project just in case anyone wants to order it.

I added a 12V AC external power supply with a 2.1 barrel plug to the project, so remember to remove that in case you don’t want it…


What you did, vonkhades, is putting a DC power supply in that Mouser list… No good. :slight_smile:
(I should’ve paid more attention when ordering)