Getting weird trace

[BladeRunner]

Hi,
completed my Kit few days before and have got a big problem:
The scope boots up, no Problem there. LCD is fine, all Buttons work.
All voltages are as they are supposed to be ( I measured all shown in the assembly guide).

But: I don't get a meaningful trace, only rumble. the Readings jump in extremes from high to low.
Changing Voltage/Div doens't change anything, just readings that max out.
I first thought I did connect the BNC wrongly, so I soldered that out, but even without BNC I always get the same.
Checked the board multiple times now and can't find bad solderings or the like. Also, as mentioned, all voltages are just fine.

Here's what i get.

Any ideas where the problem could be?

[adam]

Is that the test signal?

[jye1]

It is noise. One of possible causes is that there is large noise at the input of ADC (pin19 of TLC5510). This could come from power supply. Please try the following.

1 ) Remove BOB5 (the negative power generator). Use a independent power supply and apply -5V to substitute BOB5.
2 ) If the work of 1 ) does not make any difference remove BOB4 and close JP3. Use USB as power and see if the noise is still there.

Please set couple switch to GND to make sure input is zero at doing above tests.