Realforce R2 PFU - Detachable USB-C Cable Mod

This is a small attachment piece I designed to bring your Realforce R2 Topre keyboard closer to modern mechanical keyboard standards with the ability to install a USB C breakout board for detachable cables!

Warning!

This mod requires some familiarity with a soldering iron, wire crimping, and some basic knowledge of electronics. I am not responsible for any damage you do to your board by trying to attempt this mod.

This mod also requires some slight modification to the keyboard's housing (explained at the beginning of the Installation section).

About USB-C Cables

The mount was designed for my USB-C cable specifically. However, cables can vary in their housing size. So, before soldering anything or cutting/crimping cables, do a simple test fit to make sure your USB-C cable will fit. If you find that it doesn't fit, either try a different USB-C cable, or you can modify the provided CAD files to suit your cable. If you don't want to do either, then you could cut a small bit of the opening on the case to make room for your cable.

Hardware

• Pololu USB 2.0 Type-C Connector Breakout Board (usb07b)
  • This mod was designed specifically for the usb07b variant. The usb07a model is slightly longer than usb07b which means it won't fit in the mount once installed into the case.

• 2x M2x4mm Screws
• 1x JST PH 2.0mm Male + Crimping

Installation

You can click on the images below to enlarge them.

First of all, print out the mount on your 3D printer (no need to rotate the model, print as is from the file for optimal results), then open up your Topre keyboard and have a look at the cable routing channel which guides the USB cable. Looking at the image on the right, you need to cut off the two plastic pieces highlighted in red. This is to make space for the USB-C breakout board.

Image from user u/CharlesV_ on reddit.

Next, solder wires with a decent amount of length, so as not to put strain on the cables, strip and crimp the other end to a JST PH 2.0mm Male connector (hint: you can reuse the connector from the original USB cable of the keyboard, just carefully remove the pins from the connector without damaging the connector itself). Make sure the cable matches the original wiring of the USB cable that was originally installed with your keyboard (I recommend taking pictures as you go for reference). The cables can then be correctly soldered to the breakout board. Color reference for the image on the right (order is left to right): Red = VBUS White = Data- Green = Data+ Blue = Chassis ground Black = GND After the soldering is done, I recommend that you use a multimeter to confirm that there are no shorts anywhere and that each pin has been soldered correctly to the breakout board. You also might have to swap around the Data- and Data+ wires on the JST connector end depending on your setup. If you mix up Data- and Data+ it shouldn't damage the board, but it won't be recognized by the computer. Just swap around the cables in that case and you should be fine.

Once the wires have been soldered, attach the breakout board onto the mount using 2 M2x4mm screws.

Then, slide the mount onto the cylindrical mounting extrusion, plug in your new internal cable into the mainboard, reassemble your keyboard (ensuring that your cables are not being pinched by anything when closing), and done! Enjoy your new detachable cable!