Disassembly and Hasu Controller Mod

As far as plastic case keyboards go, disassembly of the Leopold FC660C slots in among the harder ones. First up, there is a hidden screw underneath the telltale "OK" sticker, ripping through which to get to the screw will void the warranty. A Phillips head screwdriver comes in handy here, and then comes the trickier part of getting a thin, flat object to pry apart the interlocking tabs keeping the two pieces of the plastic case together. I had to be extra careful here since I did not want to damage or leave telltale signs on this loaner unit, and having specifically made tools for disassembly came in quite handy on this tight tolerance case design. At this point, the top panel completely separates to confirm the ABS plastic construction. There is an internal cable connecting the larger PCB to the smaller one that is still on the bottom case panel, which needs to be dislodged on either end to separate these two sections as well. We now see two more Phillips head screws keeping this smaller PCB in place, which is really the primary PCB in terms of hosting the USB microcontroller, and removing them helps lift it off for further examination and the replacement itself.


Solder quality is exceptional here, with the tiniest of solder blobs left with each job. We can get a closer look at the set of four dip switches, which you will lose with the Hasu mod, as well as the stock controller that comes hidden underneath a sticker and another attempt to hide its identity by a paint stroke. Clearly not good enough a job since we see the use of a Fujitsu MB90F337 16-bit USB microcontroller. Fujitsu also happens to be the official distributor for Topre keyboards in many regions, either by itself or via its PFU Ltd. subsidiary. If I had my tinfoil hat on, I could say a few choice words about this relationship and the basic functionality offered here, to where the mechanical keyboard community got together to create a replacement controller compatible with open-source firmware for full customization. Enter the Hasu board again, which you can see adopts the same dimensions and form factor as it pertains to the I/O, although far simpler in construction. Installation is trivial—just reverse the steps from before with the cleaner side of the PCB facing you. The hole in the case where the dip switches were poking out from before now has the flash button on this newer PCB visible.


The larger PCB merely hosts the switches, but it is equally important since it has the electrostatic capacitive pads that help with actuation. This PCB is also green, with fewer components soldered on compared to a typical keyboard PCB given the primary controller and I/O is on the other PCB we just saw. More screws secure the switches and steel plate in place on the PCB, which you can remove to access the conical springs and rubber dome sheet similar to what we saw employed with the NIZ Plum keyboard. As is the norm, all the components are soldered onto a multi-layer PCB.

Before we move on, be advised that disassembly may void the warranty and that TechPowerUp is not liable for any damages incurred if you decide to go ahead and do so anyway. This is especially true for the Hasu mod—it definitely voids the warranty!