I have this older Tektronix scope a few months now. I was playing around in XY-mode and have measured some zener diodes with function generator connected to it, with current sensing resistor of 100 Ohm. I noticed that the curve has the expected zener shape, but was not centered around the zero (X-Y crossing). It was shifted some 1.5 divisions to the right. When no signal is connected I see a dot at that same shifted spot. When the test signal (sinus) of 6Vtt is connected I see a diagonal line (instead of a horizontal one), shifted that same 1.5 div to the right. In the normal mode (time sweep) I see no problems. I have tried 2 different func.gen's (same display). On my Siglent the line is centered and horizontal, as it should be. Any idea where this shift and tilt comes from? I have never noticed any deviation in time or amplitude direction when using it in the normal time sweep mode, actually quite accurate amplitude and period. There is obviously some offset/shift in XY-mode. Adjusting the offset voltage +/- of the func.gen. in only moves this diagonal trace to the top-right / down-left, at the same angle. The Ch1 amplitude (read from the X-axis) seems correct. TIA
Changing the V/div doesn't change the angle of the diagonal trace. The amplitudes are correct.