I now own a computer I've been wanting since the '80s for no reason other than it's as utterly cheap in price and quality as a fully functional home computer could get: A Timex Sinclair 1000. The picture quality is delightfully crappy. Unfortunately, half the keyboard doesn't work, which probably means its super-cheap ribbon cable kinked & broke.

@arielmt If you haven't solved it yet, it might also be worth checking the pull-up resistor SIL - *could* be some dry joints there.

(I built one from a kit, and, being a bunny of very little brain, didn't notice the polarity, so one keyboard column was dead until they fixed it, largely wiping out the saving in not buying it built =:)

@porsupah Oh, it's definitely the keyboard ribbon in both cases. They all but completely disintegrated in both ribbons at both bends.

I should probably give the boards a thorough once-over all the same. The video quality from one-meter RF cables is worse than a low-power TV station over 100 miles away.