Hello,
I've just got a new Siglent SDS1104X-E, and as soon as I started the probe compensation I noticed a rather odd artifact. I've seen lots of other issues on the forum, but not this one:
Viewing the 1kHz calibration signal with 1X probe is fine from 10V/div to 200mV/div. When I go to 100mV/div (and the relay clicks), the bottom part of the square wave turns into a ramp (please see images for a clear understanding). The steepness of this ramp then varies with turning the vertical positions (not zoom) knob.
1Xprobe - 500mVdiv:
1Xprobe - 100mVdiv:
I noticed that the problem didn't appear when using the 10X probe setting, so I decided to go back to 1X setting and manually attenuate the signal using a pot across the calibration terminals:
- Reducing the amplitude of the square wave from 3.0V to 2.7V (checking amplitude by going to 500mV/div) causes the ramp to become less steep, and for the lowest point of the square wave/ramp to rise to 330mV (which the oscilloscope also reports from the measurement figures)
- Reducing the amplitude further makes the offset go back down, and the ramp disappear, until the square wave looks completely correct when it's amplitude is at 1.25V.
- All of the changes described above are continuous and change smoothly as I turn the pot to change the calibration signal amplitude:
1Xprobe - signal attenuated to 2.62V - 500mVdiv:
1Xprobe - signal attenuated to 2.62V - 100mVdiv:
1Xprobe - signal attenuated to 1.20V - 500mVdiv:
1Xprobe - signal attenuated to 1.20V - 100mVdiv:
The images explain it best, but here are some other points:
- It happens regardless of triggering or coupling mode
- It happens on all channels
- If you stop the acquisition at 200mV/div and zoom in to 100mV/div, the waveform does not develop the ramp problem
- If you stop the acquisition at 100mV/div and change the vertical positionin, the ramp does not change steepness. (these checks are to rule out a memory problem)
- firmware 7.6.1.20 R2
I can't think of anything else for now. Hopefully I'm not just doing something daft!
Any thoughts appreciated...