X10 Probes and some strange behaviour around the 2,5,10v DIV

[justblair]

I have been probing about a bit more and the results are worrying… I am hoping that there is some way that this can be fixed.

I have measured the voltage of a switch mode power supply and I am still confused. Prior to this set of tests the probes adjustment capacitor was calibrated against a square wave.

First of all at 1v/div or lower, a 24v Power supply gives a reading of 7.6v. This is not a major suprise, I am guessing this is the max limit of this particular scale.

At 20v/div or higher I get an exact 24v reading, this is great, the power supply is hardly used and has clearly been calibrated well at the factory. I get the same reading with my multimeter. I was pleased with this result as it shows that the scope is capable of reading higher voltages accurately.

I am unsure as to why the 2v,5v and 10v are not giving readings…

@FreeZinG

The different probes have different impedance, and when you change the probes , you need to change the compensation capacitorfor of each input channel . we have modify the compensation capacitorfor the Probes we supplied .

you use the X10 probes , the impedance is far different from ours ,and the mensuration is not accurate.you need to modify compensation capacitorfor to right value for your probes.

I understand this, but I am suprised I get no reading at all. Looking at the schematic, I notice that the HC4051 works as a voltage divider? I can see that the waveform may be distorted by incorrect capacitance, but I dont see how this mechanism creates a zero reading?

I also had a look at the 1x probe and I am seeing some other issues with measurements…

Using the 1kz test signal on the DSO Nano corner with either the supplied probes or my own modified probes I get identical results (good news again)

However I am noticing different measurements depending on the v/div range used.

10v/div = 2.00 v avg
5v/div = 2.00 v avg
2v/div = 2.16 v avg
1v/div = 2.04 v avg
0.5v/div= 2.04 v avg
0.2v/div=2.04 v avg
below 0.2v/div = 384mv ie no reading. =

The 2v/div figure stands out compared to the other readings?

At the end of the day, modifying the 10x probe to work with the nano I would still say is worthwhile. Results are looking consistent between the 1x settings of the modded probe and the flimsy supplied items.

At 10x, obviously the 2v, 5v and 10v/div are not working which is pretty limiting.

But the other waveforms are there. 10x probes offer usually better results looking at a square wave, with an adjusted cap, the waves are near square, on a 1x probe are more consistent. If there is something that can be done to fix the missing div ranges it would be preferable…