Thread: Zx81
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Old 21st Mar 2020, 10:17 am   #118
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 8,516
Default Re: Zx81

And this also happens when you don't have a RAM pack connected?

Sounds like a thermal-related problem. The best way to hunt for this would be using freezer spray - let the unit run until the faults appear and then spray each major component - regulator, ULA, Z80, memory IC, one at a time to see if that makes the fault disappear. Any electroyltic capacitors in the unit are also a possibility (spray those too).

Freezer spray made for the purpose of diagnosing thermal electronic faults is usually quite expensive but if you take a look at this thread, someone has just discovered more or less the same product being sold for an entirely different purpose, and much more cheaply.

If you can bring yourself to buy some of that, that should work quite well for the purpose.

Last edited by SiriusHardware; 21st Mar 2020 at 10:38 am.
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