Does it get better, or WORSE, with extended use?
Sometimes, oxidized or dirty contacts clean themselves a little with more
use, and are especially bad with non-use.
40? years ago, I was handed a "dead" TRS80 keyboard. After repeatedly
beating on one key, it gave a hit! And, would work a small part of the
time. I tried with others, and determined that extended excessively heavy
use seemed to re-enable keys, at least sporadially!
So, I dug out a Rochester Dynatyper Keyboard Actuator. It was like the
KGS80, a box of solenoids intended to be set on top of a typewriter
keyboard to turn a typewriter into a cheap printer (back when "cheap"
computer printers were a thousand dollars). Those would "print"
relatively reliably at about 8 characters per second. There also existed
the Escon (Walnut Creek) Model E-P, which was the same idea but Selectric
specific, and mounted inside the Selectric, and pulled the keys down; that
could almost handle the 14.8 characters per second maximum of Selectrics.
I set the Rochester on top of the keyboard, and sent enormous text files
to "print". After a while some of the keys were working! By the next
morning, they all worked!
Before trying that, consider that if the problem is mechanical, it might
help those keys, or it might wear them out, and finish killing them.
--
Grumpy Ol' Fred [email protected]
On Tue, 6 Oct 2026, Charles Morris via cctalk wrote:
I'll check the p/s, but since everything else works correctly, I suspect
dirty key contacts and a poor debouncing circuit.
Pressing (for example) the "2" key, sometimes it outputs "22",
sometimes "2v"... the debounce circuit should take care of the first,
and the second has falsely set bits (0x32 vs 0x76).
Some of the other keys have either or both errors too - will have to log
the errors associated with each key and see if I can find it in the logic.
