In the following screenshot I have all 4 MSO channels attached to the ground and signal of the included Saleae pulse generator. I have all 4 channels set to the defaults with a 10V range and 0V offset.
Each of the channels is showing a different ground offset from -88.6mv to -303.07mv. I have swapped the scope probes around and confirmed that these offsets stay with the MSO channels. I have also tested with third party probes and I see the same offsets.
Looking a the calibration certificate for my MSO, the 3V measurements were all within ±1mV. I also have some captures from when I first received the MSO that show much more accurate ground measurements.
Is there some form of calibration I can do on the MSO to correct these offsets? What could have caused the calibration to get this far off in the first place?
