Converting fujitsu leaf spring keyboard

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CarpCharacin

15 Aug 2019, 09:59

I found a Sanyo MBC-885 keyboard for sale with the desktop connector, and I'm thinking about buying it, because I heard that they had Fujitsu leaf spring switches, but I'm just wondering, how difficult would it be to convert it to USB?

PancakeMSTR

21 Aug 2019, 21:51

Long story short - I think it's kind of hard.

I'm also interested in this, though, as I just picked up an Epson something-or-other, I'll post the model number this evening. I believe @snacksthecat has experience with converting Fujitsu leaf springs and could offer some advice/suggestions. He also commented a link to a guide about a year ago, but it doesn't work anymore. I was thinking about asking him if he knew another way to view it.

From a little bit of research I've been doing it looks like the most common way of converting fujitsu leaf spring boards is by handwire, but I was thinking about reaching out to the QMK people/snacksthecat to see if we could figure out how to convert it with its native protocol, although it might be kind of hard.

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snacksthecat
✶✶✶✶

21 Aug 2019, 22:03

PancakeMSTR wrote:
21 Aug 2019, 21:51
From a little bit of research I've been doing it looks like the most common way of converting fujitsu leaf spring boards is by handwire, but I was thinking about reaching out to the QMK people/snacksthecat to see if we could figure out how to convert it with its native protocol, although it might be kind of hard.
I took a shot at converting the protocol but the board's limitations made it not worth it (I'll explain below). Haata actually wrote a plug and play converter for it a few years back (well the board is not 5v but once you deal with that) https://github.com/kiibohd/controller/b ... can_loop.c

Controller Replacement
This is the approach I took. You can see some details in the thread I started earlier this year.
https://github.com/kiibohd/controller/b ... can_loop.c
It's actually pretty straight-forward to do. Just a little bit tedious.
However, this approach does not overcome the keyboard's achilles heel; which is that it is only 1KRO. :(
Which leads me to my revised approach.

Controller Replacement + Diode Mod
I ended up cutting the traces on the PCB and wiring in diodes for each switch. By doing that, I can take advantage of NKRO. This was a painful process but it turned out pretty good.

If you need any help, feel free to reach out.

Edit: My comment is specifically about the Epson QX-10 keyboard

PancakeMSTR

21 Aug 2019, 22:10

snacksthecat wrote:
21 Aug 2019, 22:03
Controller Replacement
This is the approach I took. You can see some details in the thread I started earlier this year.
https://github.com/kiibohd/controller/b ... can_loop.c
It's actually pretty straight-forward to do. Just a little bit tedious.
However, this approach does not overcome the keyboard's achilles heel; which is that it is only 1KRO. :(
Which leads me to my revised approach.
Fantastic, I'll take a look!
snacksthecat wrote:
21 Aug 2019, 22:03
Controller Replacement + Diode Mod
I ended up cutting the traces on the PCB and wiring in diodes for each switch. By doing that, I can take advantage of NKRO. This was a painful process but it turned out pretty good.

If you need any help, feel free to reach out.

Edit: My comment is specifically about the Epson QX-10 keyboard
Yeah I think this is the way to go and is my plan for my Epson (Q503A, btw). I will reach out to you when I get around to working on it. Thanks so much snacks!

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