Bug regarding the test signal

[Mike]

Hello,


i see a strange behavior with my DSO150 and was wondering why i could not find a topic about it. (To be honest, i did not read all pages, maybe there is one...)
Maybe only me can see this issue, because i installed a battery and a step up.

When i zoom into 5mV/Div i can see the 1kHz Test Signal and some 20kHz Ripple. (No probe connected)
The ripple can be cause by my step up, i dont know... But why do i see the 1kHz Signal? I also can amplify this by touching the pin.

Second thing:
If i change the test signal to 0,1V, i no longer can see it with 5mV/Div resolution!

The problem here is, that the 0,1V setting is not beeing stored. When i turn the DSO off an on, the text shows the last selected 0,1V, but in reality it is again at 3,3V.
I already have the lates Firmware from 12/2017.

Of course it is no big deal, because 5mV/Div already is the hard limit of the DSO.

[RobNL]

Have you set the top switch to ground ?

[Mike]

As you see in the display, its always in DC mode.

[RobNL]

Thats the problem, you have to connect the testsignal or set the switch to ground.
Now you pickup nois from anything around the shell.

BTW, with a expencive scope you will have the same.

[Mike]

Ok,

i got it! I aditionally just thought, that it's a "bug" that the 1kHz Singal is always running on 3,3V Level in the background.