Probe calibration

[Perry]

DSO138 is a fantastic instrument. Highly recommended. Now I can spy on the serial communication on my Arduino projects.
Two comments though: The mark R38 is doubled up on the PCB. (This is not a problem if you have a look at the circuit diagram.)
I am not able to calibrate the probe. When I use the varicaps, I do not see any difference on the screen. Anyway the test signal looks fine to me, but corners are not perfect. Could the reason be that I have mixed one of the ceramic caps?

[jyephpbb]

You have purchased a counterfeit DSO138 kit. Original DSO138 kits from JYE Tech do not have the duplicated R38 mistake.

[jye1]

If you mixed the caps you won't be able to do good compensation for probe. The caps have value marked so shouldn't be mixed.