yeah, it's one of those dumbass power supplies with the 3 holes, one will have +5, next will be 3.3, next is supposed to be like an indicator light. you have to use a small phillips screwdriver to adjust them.
most people don't even bother replacing those with Sega ones, they'll just use ATX computer power supplies, but you'll have to build an adapter for them. some people make these elaborate guides about scalping motherboard connectors from dead motherboards, not entirely sure why, I found an ATX PSU extension cable that could probably do the same exact thing. you'll just have to gather up the pinout for it, and you'll have to cut your original power supply harnesses to mate the two halves.
I still maintain that with a voltage that high though, you probably have toasted buffers.