Ground Drift

[Colinsk]

I just completed building a DSO128 a few weeks ago and I find the zero point drifts while in use. Is this normal behavior for this device?

[MNTech]

I haven't seen my DSO138 drift in normal use.
The zero reference does move when the battery is to low to properly generate the minus voltage supply.

[daved]

Is your DC power supply voltage greater than 8 volts? If not, the trace may drift down as the power supply voltage drops. For my DSO138, the DC voltage needs to be greater than 7.8 volts. I run it off an 8.4v NiCd battery.