On Sunday, October 11, 2020 at 3:01:40 PM UTC-4, T i m wrote:
On Sat, 10 Oct 2020 09:34:11 -0700 (PDT), John-Del
wrote:

snip

This is the PSU OOI: https://ibb.co/VtBY4Rt

The IC is a CR6338T.

snip

Years ago when everything was discrete, we saw plenty of power supplies so badly designed that an excessive load or even a brown out would cause a catastrophic failure (Sony).

;-(

Today, an properly designed IC SMPS controller is literally pennies each, and they have all that solved internally.

Ok.

Your IC does have a soft start internal to it and overcurrent protection, so the shorted Schottky diode did not seem to destroy the IC

Phew.

(check pin 5/6 to 4, should be no short on the internal mosfet).

5/6 to 4 test out like a pair of diodes but with a low resistance
(either way) between 5 and 6?

Cheers, T i m

5 and 6 should read short as they are the common drain pin and internally tied together inside the IC. Don't use the diode scale when checking for leakage between those pins. Pins 5 and 6 are the drain, and pin 4 is the source. Out of circuit, it should read virtually open between pins 5/6 to pin 4.