Hmm might be duff power supplies. But two in one year sounds like it might be something else. Capacitors especially electrolytic degrade over time.
You might have something bad in your Amiga 2000. Electrolytics have a nasty habit of self healing. So you might have a case of a flaky component shorting out and taking out the power supply. I have also seen hard drives in the end of their life get "sticky" on start up and draw immense amounts of current. Cheap power supplies when overloaded will go boom. High quality power supplies will cut out in case of short.
But since you said it went boom on shut down it sounds like something else. More than likely a couple of big ole drives are sending a nasty spike out as they power down.
I am afraid some peoples advice of getting a new A2000 or an original A2000 power supply is really not that wise. ( no offense redrumloa ) An old power supply or worse an old power supply that has not been plugged in for some time will most likely blow up sooner than later.
Okay so you want to convert an ATX power supply to an A2000 it really is not that hard, But there is something you will need. A tick board to convert the AC line cycles to a 5 volt 60 cycle tick. ( you might be able to salvage the one in the old supply ) Also you will need a small wake up and shut down circuit for the ATX. Yes if you connect pins 14 and 15 it will power up the PSU. but don't power off the ATX power supply by turning on and off the AC by the service switch. That will stress the switching power supply something fierce and likely cause the thing to go boom in rather short order. If you need a board or help please Email me.
Remember most PC supplies are constructed rather cheaply. So if your have a choice spend a little more money. A cheap PSU will give you random crashes and will most definitely shorten the life of your machine. Short of testing a power supply, there is really no way to accurately judge quality. But there are a couple of simple rule's of thumb to help. The heavier and the beefier the better. The thicker and longer the power wires are, the higher quality of construction.
Email me or call
better yet since you live in New York come by my shop. We can help!
Info@revanchellc.com
631 249 5185 There is normaly someone in the shop between 8:00 AM and 8:00 PM EST Mon-Fri