Eurorack Modular Synth Power Supply

Introduction: Eurorack Modular Synth Power Supply

About: GMSN! is a AV Maker Lab based in Glasgow, Scotland aimed at creative professionals looking to expand their knowledge and skills, in areas such as modular and video synthesisers, analogue, digital and embedd...

In order to build the Pure Power you will need the following tools:

· Soldering Iron

· Solder Wire

· Snips

· Phillips Screwdriver

The kits are available from

Step 1: Populating the PCB


Populating the PCB is best done starting with the lowest components in height, moving up to the highest. This helps to keep the board stable whilst soldering.


First we’ll start off with the resistors.

There’s only one value of resistor which makes it nice and simple.

Step 2: Ceramic Capacitors

Check out for more info on identifying capacitors.

Simply place through the holes and solder in place. The ceramic caps can go in any way round.

Step 3: Electrolytic Capacitors

All the electrolytic caps are the same value but ensure they go the right way round with the long leg in the hole marked +.

Step 4: Power Headers

Here’s a little soldering trick for headers. It can also be used for DIL Sockets...

Fill one hole with solder.

Then hold the header in place while heating the solder from the other side. The socket will then pop into place and you can solder the rest of the pins without it falling out.

Step 5: 5V Regulator and Heatsink

Place the heatsink on the 7805.

Then bend the legs over, ENSURING THEY AREN’T TOUCHING THE

Then solder in place.

Step 6: DC Power Socket and PCB Mounts

Solder the power socket and PCB mounts in place, ensuring they are all square and flush with the board.

Step 7: DC DC Converter

This is the main component of the power supply and contains all the over and under voltage and current protection.

Step 8: LEDs and Front Panel

Bend the legs of the LEDs ensuring the flat side of the LED is on the correct side.

Fit the LEDs in place, BUT DO NOT SOLDER YET.

Attach the front panel with the screws, poking the LEDs through the holes.

Finally solder in place and snip the legs.

Step 9: Testing and Calibration

The Pure Power module is incredible simple, so there’s not a great deal of testing to be done.

Supply voltage checks


· Volt meter set to DC volts

Connect the power supply and ensure the three LEDs light up.

With the black probe on the metal tab at the top of the 5V regulator, annotated in blue, and the red probe on each of the pins indicated in red, you should get +12v.

Now move the red probes to the pins indicated in green and you should get -12V.

Finally move the red probes to the pins indicated in yellow and you should get +5v.

Fault Diagnosis

To be perfectly honest, it’s very rare for a circuit to work perfectly first time. If you are having problems follow the steps below to fix any issues you might have.


By far the commonest issue is joints soldered incorrectly. Simply apply the hot soldering iron to all the joints to melt the solder. Hold the iron on for a couple of seconds to let the solder suck into the joint. Once you’ve done this retest.

Components in the wrong places or the wrong way round

Triple check all components are in the right place. The photos above will show you where all the components should be.

Step 10: Finally…

I hope you’ve enjoyed building the GMSN! Pure Power. We can’t wait to see what you’re going to do with it.

You can now go on and build a complete Eurorack Modular Synthesiser. All the kits are available at

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    DIY Hacks and How Tos

    Great tutorial. Kits are a great way for people to get started in building electronics.