How do I test a Mac Mini's power supply with a multimeter?

[raspberries]

can anyone explain/show exactly which pins/contacts u touched with the probes? a friend saying he has extensive (non mac hardware experience), i have to know exactly which wire/contact to probe and the other probe should be on a ground. and each wire would have a different voltage (which i've seen is true on the youtube vids for windows pcs ATX psu connector and they have diagrams for each wire and its voltage.) friend also said if a probe touches two contacts at once it could short out the PSU. in all the posts here/ifixit... it appears it doesn't matter which (of the above images) wires/contacts you touch and it doesn't matter if u touch two contacts at once? thank you!

 

[Fishrrman]

I'd much rather have an EXTERNAL power supply with the Mini.
Keeps the high voltage OUTSIDE OF the Mini's case.
Easy to swap out if it fails...