I have had a 2250 MSO 'scope for a couple of years. I now find that there seems to be an error on the vertical axis scaling. When I apply, say, a square wave of amplitude 3.3V my scope displays amplitude of 2.75V, ie it reads low by about 17% (83% of actual value). I observe the same error:
On both channels
With probes set at x1 or x10 attenuation.
With a probe from another scope
With AC and DC coupling
As measured by screen grid, or horizontal cursors, or using measurement facility.
With low frequency or high frequency pulse or sine signals, or even just DC.
Have I inadvertently set some kind of scale factor, or some other setting that could cause this?
Or is my scope faulty?
Thanks for any help.