Hello all,

I've replaced CR20 and CR21 but the same problem still remains; no activity from the Macintosh.

On the upside, I can hear a quiet electronic buzz coming from the Macintosh.

After the repair I measured the voltages from the floppy port:

+5v = 0.68

+12v =0.05

-12v =1.75

I think I'm getting close to a solution but I don't know where to look next!

Could it be a failed flyback transformer? Or some other component?

Any help would be much appreciated!