I have a (very old) Mac 512k and a Mac Plus, both of which 
have the same problem.

Their screens blank out, sometimes after a minor physical jolt
(such as inserting a floppy in the internal drive), sometimes 
all by themselves (computer left to itself just goes blank).

I have replaced the wires connecting the logic boards and the 
video board, because it seemed at first that jiggling the wires
made the screen come back on.  This worked for a while, but the
blanking out has returned.

Can I do anything?  Do I need a new power supply?  A new CRT?
A new computer?

Thanks for any advice...

--------------------------
Ethan Bodin
Tufts University
ebodin@pearl.tufts.edu