How to fix this scope?

Sound like a loose or dirty internal connector or buss connector problem.

I would remove cabinet, pull out cards, clean edge connectors with alcohol or
contact cleaner, and reseat for starters.

Any dip packages in sockets, carefully pry up a little each end and reseat by pushing
down on them back into socket. You don't have to pull all the way out, like just 1/8" movement.
That helps wipe the contacts again.

Regards, Dana.
 
Cookies are required to use this site. You must accept them to continue using the site. Learn more…