I spent quite a few hours trying to figure out the missing 12V situation with the Mac #Performa630 yesterday. At least I narrowed it down to an actual power supply problem, disconnected everything else that uses 12V (at least as far as I understand). I tried to find faulty components in the psu but to no avail so far. Shelved the project for now. Probably the reasonable solution (especially since there are no schematics and I suck at understanding smps circuitry) is to replace it altogether.
New video! In the second part of the series, I'm trying to resurrect the Apple Macintosh Performa 630 Power Supply I found to have lots of leaky capacitors in the previous episode.
New video! I'm starting to restore a very interesting Apple Macintosh Performa 630 in the DOS Compatible variant. It has both a 68040 Mac and an IBM compatible 486 PC in one machine. In the first episode of this series, I try to make it safe to run by replacing capacitors on the main board and in the power supply. More to come!