I get no 5v power right at the power supply pins
while getting 3.0 and 11.87 on the pins at the p/s
also tryed to check at the m/b power in and got power there also
but apple split the m/b power into two connectors and I have no chart or idea what pin # at the M/B unlike the 27 that has one power connector into the M/B
I think the link shows the 27'' not my 21.5 pin out at the M/B but the numbers match the 3v and 12v pins at the power supply of my 21.5 unit while the 27 power is in one block in at the M/B connector
27'' link
https://d3nevzfk7ii3be.cloudfront.net/igi/moS64VEIPaD6QDkR
can you confirm that is the M/B pin out ? and if it the same as the P/S
as I am basing my hunt on two assumptions one the 27 and 21.5 P/S is the same for pin # volts
and the 27 M/B pin# are the same as the 21.5 at the P/S
that looks to be correct based on the volts at the P/S except for the missing 5v
apple appears to use a common ground for all volts to the #1 pin and no neg 12 or 5 v lines
that PC power supplys have
don't really need pic of the apple as the PDF has a lot just no diagrams of the pin# or schematic
of the M/B or P/S guts
a pic of the suspected ''fuse'' would help and where to get a replacement
I can solder and have removed&replaced chips on a tv CB before with success [with a net tutorial to follow]
no rush as I am still mucking about on this unit and have a working PC