- Generator, the knob to change the frequency: turn left -> -10 , turn right +1
- CH1, probe to ground: never read 0V, but depends on vertical scale:
Generator Knob behaves like this only when decrasing from like 1MHz to sub 1Mhz (or 1kHz to Hz).
This is because the increments above 1Mhz are in 10kHz steps and the first decrement therefore is as well. If you are then in the kHz-range the decrements are 1kHz. I don't think this is a bug.
For your CH1 problem, this does not happen on my scope, probe to GND always reads 0V (more or less).
Also you have to adjust the scale of the math channel, this normally would be the larger scale setting of the two channels (when operation A+B is chosen).
I took my old trusted DS1052E, connected MSO5.CH1 to DS1052E.TestSignal:
(RigolDS1.png)
1V offset from ground.
(exact same behaviour as the MSO5.TestSignal)
I then plugged DS1052E.CH1 to MSO5.TestSignal:
(NewFile0.bmp)
The test signal is perfect, ground aligned.
When I unplug every channel on the MSO, no one goes to gnd.
(RigolDS0.png)
And with the math(A+B), it just confirms the numbers, the crap B is reading.
(rigolDS2.png)
I really don't understand what's going on, bad scope?