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SiriusHardware · 24th Mar 2020, 1:00 pm

It does look that way, sorry. You could check other things, for example make sure the +5V supply is 5V when the machine is cold and is still 5V when the machine is running warm and the fault has appeared.

Cooling the ULA may just allow it to run on a bad supply voltage for a little bit longer (stranger things have happened). But at the moment it does look as though you have a thermal fault on your ULA.

24th Mar 2020, 1:00 pm	#162
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,546	Re: Zx81 It does look that way, sorry. You could check other things, for example make sure the +5V supply is 5V when the machine is cold and is still 5V when the machine is running warm and the fault has appeared. Cooling the ULA may just allow it to run on a bad supply voltage for a little bit longer (stranger things have happened). But at the moment it does look as though you have a thermal fault on your ULA.