Quote:
Originally Posted by SiriusHardware
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.
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The input voltage is +15.5V, I found another 7812 on an old PCB fitted it and its giving +12.02 under load so I go with that.