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SiriusHardware · 8th Oct 2021, 2:55 pm

Assuming this is similar to ones we have worked on in the past there are actually two +5V regulators with the outputs not tied together, so for both to have no output implies failure of something common to them both, possibly the input to the 5V regulators. What voltage do you see on the cathodes (ringed ends) of CR10 and CR11?

If you had the board out and the connectors disconnected to fix the original fault, look especially carefully at the power input connector J8, make sure none of the solder joints on that connector are cracked.

Well done fixing the original screen fault, by the way.

8th Oct 2021, 2:55 pm	#2
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,553	Re: Commodore PET 2001 voltage regulators Assuming this is similar to ones we have worked on in the past there are actually two +5V regulators with the outputs not tied together, so for both to have no output implies failure of something common to them both, possibly the input to the 5V regulators. What voltage do you see on the cathodes (ringed ends) of CR10 and CR11? If you had the board out and the connectors disconnected to fix the original fault, look especially carefully at the power input connector J8, make sure none of the solder joints on that connector are cracked. Well done fixing the original screen fault, by the way.