Were you able to diagnose what's wrong with your ZX81? Usually it's a simple problem, it just takes a while to diagnose.

BTW, if you do want to get rid of it at some point, it would be nice if you could sell it on ebay or locally. The number of ZX81s left will just keep going down and they are quite decent for learning about electronics/digital systems.

It was not unseen to replace the original "keyboard" with mechanical one back then. The membrane keys were awful.

Why didn't you chop the excess from the sides of your mechanical marvel especially considering you had removed all the key caps?

It's super cool. I did a lot of zx81 hacking back when I was very young too.

I loved hacking Sinclair machines. I still have my first ever ZX Spectrum, complete with holes in the case and reset button mod.

The ZX printer brings back memories too. I remember naively printing the source code for a game I created only to come back later and find it completely faded and unreadable.

Unrelated, but I thought I recognized that username, thanks for making rclone!

What's the keyboard from?

I don't remember I'm afraid. My dad ran a business making keyboards at the time and he was always bringing home keyboards he'd bought to examine.

When he was through examining them I got to play!

Definitely looks to be from a DEC terminal of some kind, based from the switches and layout :D