DSO 138 GND Error

[Voresh]

Hello Folks,

after accidently exceeding the input voltage on my DSO 138, i get weird readings on my scope. For one, the Measuremt shifts around, and second, there seems to be a capacitance on the GND. Is there a way to fix this?

[davef]

I see you have it set for maximum sensitivity and maybe what you are seeing is just some leakage of the input signal though SW1A to the input amplifier U2B. It would be handy to trace the calibration signal through to U2B, however needs another oscilloscope.

Maybe, show pictures in the AC and DC positions. Trying the different sensitivity switch positions might give you a clue to which area might be at fault.

[Voresh]

Thanks davef,

i will try that