@Blatboy
When you said smoke did it smell like caps leaking in air spray form ?
Smell is really hard to miss as it smells awful.If Amiga was still showing
picture when smoke came out then caps are your culprit.
Even if they are just a little rised on top you should replace them first ,
some atx PSU won't turn on with blown cap and you should really check
the bottom cause they get bad there as well as the top.
As for the rest components (from experience of fixing mostly ATX PSUs)
the component that fried is black and looks fried , i used that test mostly
No experience with A3000 PSUs though.If you get it running (or convert
to ATX) you can check the voltages by setting multimer to 20 V and check
every line (using PSU chasis as ground).Make sure it's quality ATX PSU as it needs -12 V more than regular PC does.
White translucent stuff is just there to keep components in
place and can be safely peeled away
On the side note , close PSU before testing voltages on pins ,
I didn't bother to do that until it blew spark in my gazing eyes.
If it blows up closed it's less of a problem.
