Apple ///+ Power Supply

Greetings all,

Longtime lurker, first time poster...

I've got an Apple ///+ that has a bad power supply. When turning on the machine, I get a rapid "flupping" noise with a corresponding brief flash on the monitor. This is new - before it seemed it had RAM issues

I assume that something is over-volting or crowbar-ing in the supply. All I can find about the possible differences between the /// and ///+ power supply is that the ///+ supply was "upgraded" from the original.

All that said, my questions are these:

Are the two power supplies close enough that diagnosing the one is the same as diagnosing the other?

Any ideas on what I should look for or check for on the bad supply?

Are the two supplies close enough that I could use a regular /// power supply vs. a specific ///+ power supply?

I have a working /// that I could swap out the supplies to further test the ///+ but I don't want to do that if they don't interchange.

Any help, pointers, or offers to sell me a replacement are welcome.

TIA,

ScutBoy