Sinclair ZX80 / ZX81 / Z88 Forums

Long delay for an update - see below! On top of the original work (replacing the Z80, voltage regulator, RAM, electrolytic caps and PSU) I also reflowed all of the joints (by the state of the soldering I suspect that this was originally a kit) all to no effect. It took a while but I managed to track...

Thanks for all your advice - will try tweaking the pots further (instructions do not state what they actually adjust!) and attempt cooling to narrow down the issue and report back!

Thanks Mark, Definitely a PAL TV (I'm UK based) and have seen the same issue on multiple TV's. It's certainly very odd as at first the display is rock solid (although with fairly heavy jailbars) but goes this way after 10-15 minutes of use, however the rest of the machine continues to function as no...

I'm finally getting back into the ZX81 saddle after 35+ years, purchasing an "untested" issue 1 ZX81 from a well known auction site (I knew the risks but fancied a challenge!). I'm trying to diagnose a couple of issues but am increasingly beginning to think I may have a ULA (2C184E) issue: When firs...