DSO138 Display Voltage readouts and trace wrong

[dxx12]

Hi,
my DSO138 (FW50) shows 2,5 Volt RMS, when connected to a 9 V battery. It shows 1 V for the 3,3 V Signal. The trace shows the same, 2,5 squares on the display up for 9 V batt. or 1 Square for 3,3 V signal with a 1 V setting in the display left bottom corner. I put a 22 uF condenser over the trimm condensers because they both do not work.
How ca I adjust, that 9V makes 9 divisions on the screen and readouts?

[Andbro65]

Hi,

I don't understand, my oscillo give me a wrong measure on battery 9V. But it's ok with an adapter 9V.

Good luck