In this case, first thing to do to narrow the problem, is to remove the DC/DC supply completely. Unplug any and all drives from the STacy. Feed power to the Stacy through the Floppy power cable that's attached to the motherboard as alanh shows here: viewtopic.php?f=15&t=22327&hilit=stacy+power+floppy&start=400#p221915
You need an external display for this to work. If the Stacy powers up, your problem most likely is in the DC/DC supply.
Here's the capacitor list for the STacy. Made and twice used by myself.
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