macclassic,

Here is a diagram of the power supply for the Macintosh Classic II: https://drive.google.com/file/d/0B6j6P7lBWw-BVU5LZVA4SmRSTlE/edit?usp=sharing

Also, for reference, the Macintosh Classic/II service manual: http://tim.id.au/laptops/apple/legacy/classic_ii.performa_200.pdf

If the capacitors have leaked make sure to give the board good clean with alcohol.

Do you have any other 50 pin SCSI hard drives you can try?

I hope this helps!