Emax

agreed, if it hops about its in the scanning.  those delays are keys you
hold down right, so it misses it on the depression and gets it the next
scan.  Look for scanner chip, logic divider chips feeding it/cpu from it.
Do not trust sockets for any chips. also a gentle quick 275 degree hot aiir
pass might reflow solder if its a flakey connection, in the right area.  But
you need to understand the flow of scan data from the keyboard to the cpu
and then figure out if its moving about in a pattern, ie, missing every 3
&7th note which is on bus "n" whereas note 14 are on Y handled by a
different chip all of them eventually being joined.  Could be a feeder chip
serving the scanner.  Note, I could have it all wrong as a guess, I liked
the first bit of advice you just got.  My point is "random" is not "random",
From teh scanner's perspective the events are random (keys you push or
switches touched, nd there is a consistent non-reporting happening due to a
chip fail/solder fail in teh bus lines.  So you have to understand the
pattern of what is being missed, how it "reads"..  Then zero in from there:
Bad important chip, cheap serve chip, bad socket, cold solder joint, bad
diode on a line, cap & ground issue.  Its a different way of looking than an
analog mechanical keyboard.  Lorne