Does anybody know where I can get a
Harbor freight
cen-tech 750 watt Power supply schematic, wiring diagram, repair manual?
I Can’t find the contact info on the company that Manufactures the power supplies to ask if they have a schematic I could buy.

 

It is probably hard to get parts unless they are generic.

 

Not likely to be available. At under $50, it's a throwaway item.

This is probably borderline disallowed because lethal voltages are involved.

 

If a quick search doesn’t uncover a miracle, I’d put the odds against you as approaching a million to one.

Assuming you’re trying to do a repair, I’d do a thorough inspection under good lighting with a magnifying glass if needed. You might spot roasted components or other clues.