FC660M PCB Layout Customization?


I recently bought an older FC660M because I’ve always wanted to try Leopold and this layout. After taking it apart, I noticed that there are switch slots on the PCB for a JP layout. The standard layout works great, but I was wondering if I could use some of the JP layout keys if only because I’m used to the split backspace from my HHKB.

Using some tweezers, it looks like the JP Enter, Backspace, Shift, and Space works fine, but the splits (like the pipe key from the Backspace split) or unlabeled slots do not seem to register.

Anyone have any experience with this? Any suggestions to make the empty switch slots functional?

This is what my PCB looks like (not my picture)

Thank you!

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All I know is what I see. I certainly see keys without resistors soldered in. This is not uncommon for lepold to do. For instance on the fc980m leopold solders up the in switch led slots, even though they work just fine with LEDS in them. The fc980m also had unused capacitor spots.

Basically I would not be surprised if you filled those empty spots with resistors if the Jp keys magically started working.

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Thanks for your suggestion! I happened to have some spare resistors handy and popped it on. It works!..ish. The key is now being registered, but the value of the key is 255, which I suppose means that it is an unassigned key. I might confirm later, but I imagine the rest of the unused keys will also return 255 if I put resistors on them.

Unless there is a way to mod the FC660M firmware to assign the unassigned keys, I imagine this is probably as far as it is going :frowning:

Shoot. I feel bad. I made a critical typo in my first comment. I said resistor when what I really meant (in my infinite stupidity) was diode. Judging by your response though I assume you saw past my error and did indeed put on a diode for switch in question?

No problem! I did use diodes, lol. I’m not super familiar with this stuff, so I just assumed I had the terminology wrong. Thanks for the correction!


As a note for future reference, I did test diodes on a few other empty keys, 4 total. Surprisingly, for two of them, I got values of 193 and 235; still invalid, but different from what I assumed. The other two keys were 255. Since the keys I would like to use are uniquely coded, I could probably use something like Hasu’s USB controller? But at that cost, I might as well buy a Clueboard PCB though.