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DeltaSplit75 Build Guide

In order to successfully build and use the DeltaSplit75, you’ll need the following:


  • DeltaSplit75 PCBs
  • Approximately 80 diodes (GB participants should have around 100)
  • Two DIP Sockets (Optional but they’ll make life a thousand times easier if you make a mistake or something breaks down the line. Also included with the GB)
  • Two Pro Micros (Be careful of the green Pro Micros currently doing the rounds, from what I’ve been told, they have issues which make them unsuitable for a split board – get blue ones to avoid issues.)
  • Two TRRS Jacks
  • Switches (Approximately 80)
  • Stabilisers x5 (2u)
  • TRRS cable (must have three poles on the jacks)
  • Micro USB cable
  • And of course, some keycaps. Most GMK sets will cover the board pretty well.


  • Soldering iron, preferably temperature adjustable
  • Solder
  • Wire snips, preferably ones with a flat edge for cutting close to the PCB
  • Masking tape (other tape works, you’ll use it to hold things in place when soldering)
  • Helping hand – optional but it’ll make soldering the diodes far, far easier. They’re only £5 on Amazon, I highly recommend buying one.

This serves as a sort of first draft of the assembly instructions. Apologies for the missing images around the switches, I forgot to take photos of this part. If you need specific guidance at any point, just contact me and I’ll do my best to help.

First thing you’ll want to do is get your PCBs out and familiarise yourself with which side is which. It doesn’t matter which side you start with, they’re soldered the same except for the Pro Micro which has a different orientation on each side. I would also now snap off the B from the larger side as we won't need it (B is on the left - use your case to double check which one you want to be removing) Use a knife to score along the PCB a few times then carefully snap it off. I've done this maybe 5 times now and never had a PCB break so don't be too afraid, just score it a bit first so it knows where to flex.
The images here show the right (larger) side being soldered first. Take the PCB and turn it over so you’re looking at the bottom of the PCB. So as it’s the right hand side, the not-straight edge, will be on the right. It is on this side - the bottom of the PCB - that we’ll solder everything except the switches.
Put the PCB in the helping hand if you have one and start inserting your diodes.Take your diode and bend the legs so it creates an N shape. When inserting into the PCB, you want to ensure that the black line of the diode lines up with the square pad on the PCB. For the most part, the orientation is always the same but the odd ones on the bottom row may be different so pay attention!
Take the time to look over the PCB and double check that a) you have put in all the diodes b) the orientations are correct. When you’re happy, we can solder them in.
If you’re using a helping hand, I recommend soldering the diodes on the same side as the diode itself. This has a number of advantages. Gravity handily keeps the diode flat to the PCB while you work, and when you’ve finished, you can snip the legs on the other side nice and flush. Another reason is that if you end up with a faulty diode or one fails later (admittedly highly unusual but it could happen) having the solder on this side, makes repairing it a whole lot easier.
If you aren’t using a helping hand, you can either bend all the legs flat so you can solder on the underside, or flip over the PCB so the diode ‘heads’ are against your desk and solder on the other side. It’s fine to do this, it’s just more difficult to fix later should you have any diode-related issues.
Begin soldering. Just put the iron on the pad and the leg and apply a little solder. You’ll notice some square pads below the diode head, these for a different type of diode so don’t worry about making contact with these, it’s just the hole the leg goes through that you want to be concerned with. Keep an eye out for bubbles of solder, if you get a round dot, apply the iron again so it goes flat and runs around the leg of the diode.
It’s pretty time consuming, but keep going until all the diodes are soldered. Check again that you’ve soldered them all as it’s very easy to miss one. Once you’ve finished, flip the board over. Use your wire snips to cut all the legs off and retain them. You’ll use them later to fit the Pro Micro into the DIP socket.

Next up is the DIP socket. To make life easier, we’re going to cut off a couple of the plastic bars that hold it together as they get in the way when soldering the switches in later. Use your wire snips to cut the DIP socket to look like the one in the photo - it should be a H shape. You can cut it once soldered, but it flexes a bit so you may run the risk of damaging your soldering which is why it’s better to do it first.
Place the DIP socket - still on the bottom of the PCB (use the case to check which side is the bottom if you need to, it’s crucial the DIP socket is on the bottom of the PCB) - into the holes for the Pro Micro, it should line up nice and easily. Use some masking tape to hold it in place, then flip the PCB over.
Solder the DIP socket legs to the PCB. Remember that these solder points will be hidden by the plate and switches once we’re done so pay attention to your soldering and ensure all legs are soldered well. Don’t be afraid to add a little more if it doesn’t look like a good contact. As the legs are quite sharp, you should get a nice tent-like shape going up to a point once soldered - if the solder is perfectly round, I’d recommend applying the iron again to let the solder settle around the leg. Once done, remove the masking tape.

Flip the PCB over again so you’ll be looking at the bottom again. Place the TRRS jack on the PCB and check the legs align with the holes. Due to the plastic moulding of the jacks, they do sit a little off the PCB near the front. Best thing to do is place the jack on, and use masking tape again to hold it in place. The two rear legs protrude fine, so go ahead and solder those. With the front two, solder them but apply a little extra solder. If you turn the PCB over and look at the front two legs, you’ll hopefully see some of the solder come through and run up the leg of the jack on the other side. If it hasn’t, you can add a little more solder to ensure the connection is good.
At this point you’ll want to go back and do the same thing to do the other PCB. Everything is identical, pay attention to what side you’re soldering on and again, use the case to check your orientation as and when needed.
Before doing the Pro Micro, we’re going to solder two switches into your PCB. It’s true that the DIP socket allows for (relatively) easy remove of the Pro Micro so you could, in theory, put it in first, but it’s quite easy to damage the Pro Micro removing it, so I try and avoid doing it whenever possible.
Before adding the switches, install your stabilisers where appropriate. Lube them if you have lube to hand (you can always lube them later, the plate doesn’t obscure them all that much.)
We’re going to begin soldering some switches now, so again, take the time to check which side of the PCB you’re looking at. We’re now working with the top of the PCB - it will be the side without the DIP socket and TRRS jack.
I’ve tested putting all the switches in the plate, then pushing them all onto the PCB compared to pushing the switches through the plate and into the PCB one at a time. On a larger board, the first method is probably better but for small boards like these, the second method was far, far easier and created a much more flush board. With this in mind, get two switches and put them in the plate at the same point where the Pro Micro is (the two switch points directly below the DIP socket). To make your life easier, I would also take another four switches and put them around the edge of the board just so everything is lined up.
Solder the two switches below the Pro Micro - don’t do any more yet.
Before installing a Pro Micro, you should always flash it to check it works. Pro Micros are incredibly fussy at times - everyone in the GB, I did my best to pre-flash all your Pro Micros. If your bag has been opened and stapled shut, it means I pre-flashed it and confirmed it works so you can go ahead and continue with the below instructions. If you weren’t on the GB (or I forgot, sorry!) you’ll need to flash it now. Flashing Pro Micros is beyond the scope of this guide, but the QMK firmware has you covered:
I use a Mac myself, so if you have Mac-related questions I’m pretty sure I’ll be able to help. Other OS’s, please still get in touch but my ability to help maybe more limited depending on the question.
Assuming they flashed successfully, it’s time to add the Pro Micro to your PCB so we can do some testing. If you’re following along with the right hand, larger PCB, you’ll want to mount the Pro Micro upside down. If you’re working on the smaller, left hand side, you’ll need to mount it component-side up. It’s crucial you get this right so check and check again before soldering.
Place the Pro Micro - in its correct orientation! - over the DIP socket. Grab one of the diode legs we kept hold of earlier and push it through one of the Pro Micro holes into the DIP socket. As you push, you’ll feel a small mount of resistance, then it’ll stop. If you gently pull the leg, it shouldn’t come back out easily. The diode legs are surprisingly sharp, so I recommend holding them gently using your wire snips and pushing them in that way.
Start off by putting in the top left, bottom left, top right and bottom right legs then snip them relatively close to the PCB, just leave maybe a couple mm above the Pro Micro - you just want enough to solder around. Then work your way round the Pro Micro adding legs and snipping as you go. The snipping isn’t absolutely necessary, I just do it so that the legs aren’t getting in my way when I come to solder everything.
Once the legs are in, take a second and double check that orientation! Once you’re happy, solder in the Pro Micro.
Repeat with the other PCB.
At this point, you’ll want to join the PCBs together with your TRRS cable, plug in the smaller side using the Micro USB cable and begin testing. I’m a big fan of - load it up and make sure the clicks are enabled. Turn up your speakers then using some tweezers or other implement, short each switch point. All being well, you’ll hear a click. Don’t panic if some do not work, it’s likely just the key map (e.g. Fn keys don’t tend to give a click) However, if the main alpha keys have any problems, take the time to go back and check that the diodes are soldered correctly, not missing and are in the correct orientation.
The main thing you’ll be looking for is if you have entire columns not working. If you do, you’ll want to go back and check the soldering on the Pro Micro as you may need to reflow the solder. It’s also possible that you didn’t push the legs into the DIP socket fully - if you have a dead column that isn’t fixed by reflowing the solder on the Pro Micro, I’d suggest removing the Pro Micro and checking you don’t have a short leg.
All being well, you’ll have a functioning board. You can now go ahead and push through all the switches and solder them in. When I’m building these, I solder all the switches except for the bottom row. I then get some keycaps, and fit them on the bottom row as I want them to be so I can be sure the switches are in the right place - don’t guess! You can also do this for the caps lock as it supports stepped/not stepped so you want to make sure you use the right one depending on your choice of keycaps.
Once the switches are all soldered, you’re pretty much done! Drop the plate into the case and screw it in using either an allen key or a T5 screwdriver.