As I've already lost two 1200 units for unknown reasons (Well at least one of them) and because original Amiga power supplies seem to be crafted in Hell by Cacodemons I decided to get for an ATX PSU instead.
People on the internet and on the DoReCo this year seem to replace it very often. So why not? All you need is 12V, 5V and -12V and you are done. Every usual PSU for PCs can deliver this at high currents.
I'v stumbled across this website. This guy analyzed various options for replacement and also delivers some hardware to support it.
I've bought one picoPSU ATX adapter from him and ordered the picoPSU90 from Amazon.
On Mr. Stedmans page there is also a suggestion for a printable model of a shrunken down Amiga PSU suited to contain the circuit.
I don't own a 3D printer as I was in believe that I wouldn't need one ever.
(It's also my opinion that something like this should be shared in a group as one person would probably print too seldom to justify the costs.)
But I have a friend who has one and was able to print this thing overnight on an Ultimaker 2+.
The whole result is far from perfect and not as good as shown on Thingiverse. But the printer was set on 1.5x speed so maybe this is the reason why.
I'm still happy as this is the first time I've ever 3D printed something.
What is there still to say? I'll let the pictures talk.
This beast is powered by an external 12V adapter giving 5A resulting in 60W.
The picoPSU could do more but I didn't have a fitting adapter around. But 60W is still a lot, even for an Amiga.
I've tested it and I was kinda confused. The voltage ramps of the power up seem to be different compared to the original PSU as the screen goes green and the audio gives a clicking sound after powering up. Shortly after that the screen goes black like it should when an A1200 is booting and after that the system is running.
I hope this is just an unimportant side effect. I'm not an experienced analog guy.
Apart from that this is a really nice and clean solution.