Yeah me too in 1982, using the Melbourne House Z80 reference, aged a young 10 years old. Working with POKE and no macro-assembler, I wrote mnemonics then translated them to machine-code by hand. A baptism of fire that to this day that I've not forgotten.

This book was the ignition that changed my life... https://archive.org/details/z-80-reference-guide-alan-tullya...

Cover art to die for too!

ZX Renew sells replacement membranes for £12 if you want to get it in working order.

I have my ZX-81 (with the 16KB expansion pack) and my ZX-Spectrum (with a microdrive). I think they're in working condition though they haven't been powered up like in 30+ years.

Don't just plug it in! The power supply and/or VRM can fail in ways that deliver bad voltages to components. You might want to watch some of Lee's[1] videos first on how to bring up a ZX81 safely, or ask in his discord community for more help.

[1] https://www.youtube.com/@MoreFunMakingIt/videos

Thanks for the tip! If/when I do I'll try to use a bench power supply so I can put a current limit on it.

That is why my Timex 2068 has never left the box since around 1990.

Better admire for what it was and use an emulator instead.

Watching the retrocomputing enthusiasts, apart from obvious things like water damage, it seems that the first thing that one always has to check before attempting to power up is capacitors. A generalism true for all old electronics, rather than Sinclair-specific.

And always assume the C64 power supply will fry the computer. It fails over time by raising the output voltage.