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SiriusHardware · 19th Mar 2021, 10:21 am

What is the input voltage to the regulator? The unregulated input voltage needs to be at least 2V or more higher than the regulated voltage out on that type of regulator for the regulator to be able to 'regulate'. Also look at the input voltage to the regulator with a scope to make sure the input is moderately smooth DC and not ripple-rich.

If that's OK, remove the regulator and connect a variable voltage supply set initially to 14VDC to the input and GND terminals of the regulator and see what output voltage it produces when powered independently, outside of the SMPSU. If you still get <<12V, select another 7812.

19th Mar 2021, 10:21 am	#62
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,575	Re: The Transam Triton Personal Computer What is the input voltage to the regulator? The unregulated input voltage needs to be at least 2V or more higher than the regulated voltage out on that type of regulator for the regulator to be able to 'regulate'. Also look at the input voltage to the regulator with a scope to make sure the input is moderately smooth DC and not ripple-rich. If that's OK, remove the regulator and connect a variable voltage supply set initially to 14VDC to the input and GND terminals of the regulator and see what output voltage it produces when powered independently, outside of the SMPSU. If you still get <<12V, select another 7812.