This is for all you vintage lovers. I have a Sansui 8080DB that powers up, lights come on, comes out of protect mode but does nothing else. Meters don't register and there is no sound. When you push on the pins that join the preout and mains in the back it makes the dreaded "Humming". Any ideas??

My buddy has an old Sansui that consists of numerous daughter-cards plugged into a mother-board. Every year he takes it apart (which I understand is a big job) and cleans all the mating contacts. Perhaps that's what yours needs.

Try disconnecting the amp and pre amp sections and use a different amp and pre to trouble shoot which side the trouble is on.