Chosen Solution
Does anybody have a good methodology for checking a power supply with a multi-meter? I’ve found this link to testing the PSU, but I’m not sure if it’d work with mac PSU’s as well. Closing a circuit with a paperclip sounds dodgy: https://www.wikihow.com/Check-a-Power-Su…
@hughprobyn not dodgy at all, I do it like that all the time. That is how you turn the power supply on. Problem that you will encounter is that you have no schematic and no values for your power supply. Those are the minimum things you need to check it. Of course, there is not a lot of information available since Apple is known to be absolutely paranoid and not the least bit interested in helping DIY’ers out. It will help if you can give us the power supply number. Should be something like a Delta ADP300 etc. Just to reiterate, you can’t use the test procedures show on your link for your iMac.