The problem with the PicoPSU and old hardware is simple, sometimes it just plain doesn't work on older machines. The Sharp x68000 is one such example with it's complicated soft power circuit.
Can you recommend anything that would power a Sharp X68000 Ace. The original power supply has been converted to an old ATX PSU from a pc. I was considering the pico as a replacement and a tidier job I'm trying to find a tidy solution rather than have an ATX psu outside