Author Topic: Kaypro 4 Keyboard, Teensy  (Read 1712 times)

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Offline OldIsNew

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Kaypro 4 Keyboard, Teensy
« on: Sat, 12 August 2017, 11:02:15 »
This is a cross post but I thought it was kind of a cool old board so I figured I'd post it here too. The switches appear to be most likely SMK J-M0404.

175688-0     175690-1

I traced out the matrix with a multimeter, then desoldered the ICs and hooked up the Teensy.


175692-2     175694-3


It's short a lot of the keys that are standard now, but I just like the old style boards. The keycaps are nice heavy sphericals and the switches are pretty nice too, if you like linears.

Offline Trente

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Re: Kaypro 4 Keyboard, Teensy
« Reply #1 on: Sat, 12 August 2017, 15:13:45 »
This looks really awesome, and I am wondering what setting on the multimeter you used to track down the matrix??

Offline OldIsNew

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Re: Kaypro 4 Keyboard, Teensy
« Reply #2 on: Sat, 12 August 2017, 17:37:03 »
... what setting on the multimeter you used to track down the matrix??

I just set it to the audible continuity testing setting, easier to listen for the beep than stare at the resistance on the meter. Have to pay attention to where the diodes are and not measure through them since the meter typically won't beep due to the resistance if you do.

175747-0

Offline Trente

  • Posts: 172
Re: Kaypro 4 Keyboard, Teensy
« Reply #3 on: Mon, 14 August 2017, 20:52:25 »
I just set it to the audible continuity testing setting, easier to listen for the beep than stare at the resistance on the meter. Have to pay attention to where the diodes are and not measure through them since the meter typically won't beep due to the resistance if you do.

Gotcha, tried today and works perfectly. But since the keyboard I am trying to fix do not have diodes on switches  or PCB(yep I really don't know how they manage to work), and the design of the keyboard matrix is really tricky that I completely lost my mind, so I think I would just go with hand wiring instead. But anyway, thank you very much for this helpful tips!!