Numeridex 7000C2 Oak FTM Keyboard

[OldIsNew]

I picked up this board because it looked interesting. There is a date code of 249-8219 on the board so maybe 19th week of 1982?


               


 It turned out to be an Oak Full Travel Membrane board - something I had never tried before.



A number of keys weren't working properly so I disassembled it, cleaned the parts and traced out the matrix. The keys are held in the backplate by plastic rivets similar to the barrel plate of the Model M. I removed these with a wood chisel and used silicone sealant to hold the switches in place when reassembling the board. The silicone holds the switches in place but also allows for easy removal of the switches in case further work needs to be done.

 
     


               


I used  trio-mate connectors and breadboard pins for the membrane connectors, wired it up to a Teensy and reassembled.

               



It made for a fun project and a chance to try out these switches but I can't recommend them. They are linear but rather heavy and stiff. Also, even after a through cleaning  the switches tended to remain rather scratchy as well. A plastic safe silicone lube did help with with the scratchiness but I still can't see doing serious typing on them.

[invariance]

That looks so good.
It’s what (my) dreams are made of 
Would be interesting to make a weight comparison with mechanical typewriters to understand if they are comparable.

[suicidal_orange]

I do like a huge spacebar, good work reincarnating it

Can't help noticing that a very sensible looking matrix, was the PCB is covered in diodes or does it suffer from ghosting?

[OldIsNew]

Thanks for the comments

...
Would be interesting to make a weight comparison with mechanical typewriters to understand if they are comparable.

I hadn't thought about that. It'd been a while since I've used a mechanical typewriter, but I would say the board is not that heavy though it gets into the ballpark. I guess we could give the switch designers some credit by saying that's what they were shooting for, but I'm not sure it's true, lol.

...
Can't help noticing that a very sensible looking matrix, was the PCB is covered in diodes or does it suffer from ghosting?

Yes,  I thought pretty straight forward matrix for a change! This is the matrix I traced out:



No diodes on the PCB. Maybe the original firmware used blocking to handle those issues?





A short video of banging on the keyboard: