I haven't ever looked at a 7100 scope, but I did have a 7904
with a very dim readout. If you turned the trace intensity all
the way down and dimmed the lights, you could make out the
readout characters.
In my case, it turned out to be the Z-blanking board was way
out of calibration. I went through the calibration procedure
until I got the the blanking board. When I did the board, I
suddenly had the readout. (And everything still worked as well :-)
Going through the rest of the calibration procedures showed the
rest of the 'scope wasn't that far out of spec.
I hope this helps.
- Mark
