It worked for several weeks, then suddenly went dark & the power supply let out the magic smoke.  The power supply was dropped.  It somehow cracked a fan blade, causing it to stop.  It must have over heated & fried a component.  12V was shorted to ground.  All the caps were intact.  It was probably a delaminated transformer winding.  There was only 1 more supply, a 2005 era 500W deal.  All the others from before 2001 were recycled to conserve space.  It used a PS223 protector but had no obvious voltage regulator on the low voltage side.  That was the end of computer power supplies.

The next step would be making another PWM circuit for another 90W laptop power supply.  The total number of new PWM circuits would be 2, since using a transistor as a resistor is super inefficient.