Thread: Zx81
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Old 22nd Mar 2020, 9:06 pm   #125
John Earland
Join Date: May 2013
Location: Middlesbrough, North Yorkshire, UK.
Posts: 442
Default Re: Zx81

Originally Posted by SiriusHardware View Post
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.
I've just purchased the 'Poop' freeze spray, so wil have a go tonight and report the results.
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