Strange that this caused crashes. I once forgot to wire in the -12V rail entirely and the worst I got was half-wave rectified audio (not pleasant) and failure of the serial port to operate (again, signal rectification). As soon as I realised my mistake and connected it, all was well.
I don't know how your machine is wired up, but I used both the original rear port connector as well as the motherboard floppy power header as places to inject the 0, 5 and 12V rails. The -12V rail is only attached via the rear connector, but then again, current requirement is minimal. I did find that even after supplying the HD, floppy and CD directly from the PSU, the combined draw of the 1200 motherboard, BlizzardPPC and BVisionPPC was a bit more than I was comfortable feeding in through the original power connector, which is why I decided to inject additional power via the motherboard floppy power header.
The first power supply I used was the one from my old A1500 this had run fine for years with my plain old Blizzard060, the day I got the BlizzardPPC from ebay was the start of the problems. At first I put id own to being the edge connector as sometimes but not always, it seem to cause the crashes if you just moved the boar slightly with one finger.
So I spent the next two days de-soldering the old edge connecter and re-soldering on a much more sturdier one that I had on an old 4Meg memory expansion. As I say this turned out not to be the problem as the results where just the same.
So the next thing I tried was an old PC PSU that I nicked from one of my sisters PCs, this worked a lot better but still with the odd crash. That PSU if I recall correctly had a max of 500ma on the -12V supply. So then I bought a new PSU that had -12V @ 1000ma (again if i recall correctly, suffice to say the only difference was a higher rating on the -12V) and have never seen the problem since...
That's why I put it down to being something to do with the -12V, but I can't be 100% certain as I was just so happy the problem was solved I never checked it out any further...
All power connectors on my set up are taken directly from the PSU as I'm not keen on having lots of other connections coming from the ports on the MB. Everything has worked fine for many years now using this PSU in this way and the full specs of my main A1200 are:-
Blizzard060/PPC 60Mhz/240Mhz / 256Mb RAM / 2 x 500GB 3.5" HDs / 2 X DVD-CD ReWriters / FastATA MKIII / SubWay USB / Cocolino Wireless Mouse Adapter / Custom Built Amp & Fader (for Amiga & CD Audio)
