Yep, the test signal is 1V p-p and is centered.
When testing on the normal input (AC), I center the test signal, ... everything is clear.
But when I invert the signal using the inverter switch, the test signal is still 1V p-p but a mall offset (something like 0.5V) is introduced, so the signal is no longer centered ...
Do you think that this problem is due to calibration error or a maybe a component has burned in the circuitry of the 'scope ?
Thanks for your answers.