Posting this here in the hopes that someone may be able to point me in the right direction for a fix.
Today I pulled my Obtronix out of storage. It was last used about 8 months ago and worked perfectly then.
It has a Briel Serial Interface installed, and the keyboard is from a Franklin Ace 1200.
The problem is that the keyboard is not working correctly. When I first powered on, only about half the keys worked. Over a period of about 20 mins as I tried to work out what the issue was, more keys seemed to stop working so now only about 1/3 of the keys work. It's strange that at one moment a key can be working (e.g. the return key) and moment later it stops working completely. I don't think it's an issue with the keys themselves (although I have yet to confirm that) as everything was working perfectly last time I powered it up, and has been working perfectly for about 7 years since I first built it.
I first thought it could be the keyboard encoder dying, except for another example of weirdness in that all the numbers on the main keyboard do not work, but about half of the numbers on the keypad still function fine, which makes me think it might not be the encoder after all....could be wrong.
I also contemplated the thought of some stuck bit(s) on the parallel keyboard buss, but quickly thought that if this was the case then I a key would still probably work, but produce an incorrect character on the screen.
I have also removed the Briel serial interface with no change.
Anyway, that's about where I'm at. Any thoughts or advice would be greatly appreciated.