Possible Bug with VDC / VPP DisplaVoltage when ajusting Ypos

Hello All,

I calibrated my DSO as per instructions and am seeing a strange issue or discrepancy with what is shown by VDC/VPP and the true value that is shown by both a Fluke multimeter and an Hitachi V-1100A oscilloscope.

The value shown on the DSO is incorrect even after calibration.
But more to the point the value of VDC/VPP changes when I adjust the YPOS?
The displayed value of VDC/VPP lowers when adjusting the YPOS towards the lower portion of the display and rises when moving the YPOS upward.

Anyone else experiencing this issue?

Upgraded to the latest and greatest at time of writing.

Hardware Version 2.60
Sys 1.51
App 2.52

Kind Regards,

No one else with the same issue?


Not only it happens when moving the Ypos,I calibrated my quad with minor issues some weeks ago,everything within tolerance. With this I mean there was not too much difference between the measured and the real value (calibrated first brand oscilloscope), also when switching from one .
Today I started playing around with the decive, installed marcosin’s software it and made a new calibration. I am just unable to have decent accuracy in the measurements (voltage wise).

What is more frustrating is that the value for the same input level (continuous DC) changes significantly when switching scales, IE from 0.2V/div to 0.5V/div. It might be an incorrect calibration but still I dont like the fact that the linearity of the device seems to be affected too much by the scale.

Also, when the measurement exceeds the maximum value the active scale can display/calculate, the device still shows an incorrect value. In my opinion if the calculation is “saturated” the device should indicate so.

I will try to have the calibration issue (if existing) sorted out and post my experiences here.


I haven’t played much with YPOS but my experience is, in general with HW2.6, FW1.8 of marcosin (it was the same with original App 2.52 and Sys 1.51):

  • graphical display more or less OK, but with an 8 bit A/D-converter I don’t think you can expect much more
  • Vmin and Vmax reading completely useless (e.g. DC Signal with 5 V has usually a Vmin of 0V). I don’t understand what these functions mesure - not the actual Vmin and Vmax, anyways
  • Vrms not really useable - maybe just because of the resolution of the ADC
  • often, incoherent combinations of Vpp, Vrms, DC and so on

Beside that, I have a huge offset on channel B (nothing to do with the resolution of the ADC), even though I calibrated it carefully - but in the meantime, I changed from original firmware to marcosin’s, so maybe this is the cause. UPDATE: the “huge offset” has now been corrected by calibrating.

For me, the readings on the right are more or less useless at the moment - fortunately you can hide them with marcosin’s firmware.