I'm in the process of restoring an original X68000 model, and noticed something interesting about the 2 floppy drive power connectors, the pinout is different from what's documented here: https://nfggames.com/nfg/x68repair/
The FDD connector (both of them) is a 4 wire connector with colors: Blue, Black, white, red
YES! The +5Vsb is actually sent to the 2 floppy drives! I have confirmed using my multimeter that it's the same +5Vsb that is fed into the X68000 board. So this brings up a few questions:
1) Why is standby 5V required for FDD?
2) What will happen is I omit this line or connect it to standard +5V rather than +5Vsb
I have an original X68 but it's not near me at the moment so I'm just guessing.
Possibly the +5Vsb is used so that the drives can still eject disks while the system's turned off. I wouldn't expect anything awful to happen if you went with normal +5V, but if it were me, I'd look into running the standby line anyway.
Got any pics of the connectors and wire colours?