I build a lot of DIY modules. Some are easy, and turn out great, working perfectly right away. Others...not so much. After my latest mishap—with smoke from a decapitated capacitor still lingering in the air—I decided to seek out a solution so as to minimize the possibility of creating more smoke, and that’s when I decided I needed to come up with a more thorough [and safe] method for testing new builds as my previously method always felt a little sketchy.
I have two Eurorack setups, one is a 3U 84HP skiff, and the other is my main rig, a 15U 84HP case. In my 3U I have a Tiptop Audio uZeus powering the whole thing and it’s always done a good job for me. One thing that I really like about it is that it has three LEDs—one for each power rail [+12V, -12V, and +5V]—that light up when you power up your rig, signifying that all is well. If one of the LEDs doesn’t light up, that’s when you know you have a problem. It’s happened many times to me where one [or more] of the LEDs failed to illuminate, and sometimes it’s when I accidentally plug in an assembled module the wrong way [DOH!], but most of the time, it’s an issue with one of my DIY builds. Usually it’s some boneheaded mistake on my part like putting in a diode backwards, ditto for an electrolytic capacitor, missing a solder joint, or not inserting an IC correctly in its chip holder [always use a chip holder on DIY builds!]. Truth be told, not one of the issues I’ve had from DIY’ing modules has been a fault of the manufacturer or the products themselves, all of my problems have been because of me. Whether it’s because I stayed up until 4 am soldering when I couldn’t see straight, or guessed which direction the header should go, or I just didn’t pay enough [or any] attention to the build guide. Always read the build guide all the way through before you build. Trust me, I’ve learned the hard way. Many times.
When I would finish a build my previous methodology to test it out was as follows: I had my rig plugged into a power strip with an on/off switch, so that when I power up, I have a way in hand—but not right next to my rig—to quickly switch the power off just in case one of the LEDs on the uZeus didn’t light up. In this way I can minimize any damage to modules, and so far this has worked ok; I’ve only fried a couple of modules from building mistakes and all of but one of the pre-assembled modules in my rig have survived my mishaps. Still, this method feels incomplete and a bit sketchy, so I sought out something more thorough and put together a small testing-only system that consists of a DIY power module/busboard, Joranalogue’s Test 3, a Mordax DATA, the Waveform Sound of Mewsic speaker and a few other simple, inexpensive DIY modules that I use to help test out builds [VCA, VCO, etc]. The Test 3 is the key to all of this, as along with having LEDs that light up for each power rail it measures voltages and currents of each of the power rails.
Test 3 consists of a 16 pin header in which to plug in modules, an LED screen, and two buttons that cycle through three measurements—voltage, current, and stored peak current—of each power rail [+12, -12, +5] with a total of six LEDs to signify what you’re testing. Test 3 lets you plug multiple modules in up to 1A of current per rail—helpful for measuring the exact voltage of your system and diagnosing power issues—and protects the rails from reverse voltage—also helpful. You can also use Test 3 to power your breadboard and measure voltages as your build/design comes along if you’re designing/building/prototyping. Test 3 utilizes a Mosfet protection circuit and a power header that can only be plugged in one way, which might seem trivial, but how many times have you accidentally plugged a module in the wrong way because of tiny writing—or no writing at all—denoting the correct orientation of the -12V power/red stripe, and fried something? Me? I admit to nothing.
You can’t just plug anything into Test 3 and think you’re protected, so when I’m finished with a build and ready to power it up for the first time I’ve come up with a bunch of steps that I take, and I do this whether it’s assembled module that I just purchased or a DIY build. It’s better to be safe than sorry, right? I still use the power strip technique to be able to turn the power on and off quickly, but before I even get to that part, I first do a thorough visual check to make sure that everything is soldered cleanly, the chips are oriented correctly with each leg secure in its socket, and there are no visible solder bridges or blobs. Then I check to make sure there are no short-circuits on each rail by using the continuity setting on my multimeter and testing the header pins on the module. If that checks out I will then plug the module into Test 3 and switch the power on. If all three of the LEDs on the Test 3 light up, I cycle through the voltage rails and check that the voltages being read are in the expected range of the build, as laid out by the build guide. If all of this lines up right, I’m feeling pretty good. If an LED doesn’t light up, or if something starts smoking, I quickly flick the switch and shut the power off and pull out the magnifying glass and schematic for the build, if there is one.
Test 3 is my first wave of testing, and only when it passes the LED/voltage test do I pursue further. If it passes and I want a visual of the voltage/wave/spectrum, I patch it into DATA. If I want to hear it, I plug it into the Waveform speaker and use whatever other modules are necessary to do that.
It’s somewhat ironic that Test 3 comes only as a DIY project, but it’s an easy and straightforward build so long as you read the build guide. There are only a handful of through-hole components to solder as all of the SMD parts are already in place, and the whole build took me less than an hour to complete. It’s really been handy and has changed the way I go about testing and troubleshooting my DIY builds. If you build a lot of modules as I do, I strongly recommend picking one up. In the time I’ve had Test 3 it’s saved me many headaches and smoke inhalation issues, and it’s safe to say it’s been better for both my mental and my physical health.
8 HP +12: 35 mA
Price: From $44

www.joranalogue.com