So I've used my DS1054z intensively in the last few days since I wanted to calibrate a shunt sense resistor and today I've noticed a very strange behaviour of my scope:
Every time the scope switches from 500mV/div to 200mV/div (with 1X attenuation) I hear a relay switch, which is pretty normal. The strange things start when you switch into 200mV/div:
!Some! fast changes in voltage result in capacitor charging curves/slopes, which completely dissapear when switching to higher voltages/div.
These are visual in picture 1
This does not happen with 10X probe attenuation
I wanted to add an negative offset to the waveform as seen in picture 1 to get a better view on the charging slopes, but as I turned the offset knob on my scope, the curves disappeared (picture 2). They seem to vanish proportional to the offset I add. I cant imagine how this happened, since I always thought the offset knob was just a software adjustment that basically slides the waveform up and down the screen.
I figured all of this out, when I was scoping a 50% duty cycle pwm signal from my atmega8 (picture 3)
So does somebody have an idea if my scope is broken, or if this is just an effect of an 1X probe?
Note: When I turn off the output of my lab power supply, the charging curves disappear, while my signal gets shown without a problem for half a second (till the internal caps of my supply have discharged), so is this some kind of ground loop problem? (my PSU is linear & has an isolated output)
Picture 1:
https://ibb.co/72kp79YPicture 2:
https://ibb.co/pZPF8L5Picture 3:
https://ibb.co/vZ48PCX