ATX PSU adapter for old Macintoshes - IIcx, IIci, (IIsi? should be the same), IIvx, IIvi, P600, C/Q650, Q800, PM7100. Finally a replacement to a rewired ATX extender harness.
Attention! There now is a version (alternate suffix) with oblong holes for the 20-pin connector, allowing use of ones where the pins do not have kinked legs - this was a bad oversight on my part on the first revision.
You'll need: 1- An ATX PSU (duh) 2- A single gate inverter in SOT-23-5 package (SN74LVC1G04DBVR or compatible) 3- A 100nF capacitor in 0805 package, rated to 10V or better, X5R dielectric or better 4- 2x 2.2kOhm 0805 resistors (maybe optional but probably not - can't check now, no harm in having them) 5- A male 20 position Molex MiniFit Jr. header, p/n 39-29-9205 or similar (or half of an ATX extender cable, or the ATX connector ripped off some old motherboard) 6- A female 10 position Molex MiniFit Jr. header, p/n 15-24-7100 or similar (or the harness from your decrepit Mac PSU)
It`s generally hand-solderable and foolproof. I'll provide JLC assembly files for at least the SMD parts. Resistors are probably required
I am not responsible if you blow yourself or your Mac up in attempting this. These files are provided in the expectation anyone attempting to use them is sufficiently skilled to do so.
Also thanks to https://github.com/phipli for sanity checking