Hi,
After long hours of measurements, cleaning etc. I had a final look at the acquisition board again and identified a suspiciuos via close to one of the infamous SMD caps ( see pic ).
I traced it and it turned out it was eaten up by the electrolyte.
After replacing the track with a wire the scope booted w/o errors and passed SPC.
What do we learn ?
Check all vias close to caps and pray they are not hidden underneath a part.
The broken connection carries the TRIGCC"B" signal between U1551 pin 26 and U624 pin 14.
One possible hint : SPC showed the following errors :
0x51efee4 (V main): TRIG"beta" trigGain[ CH1 ] 0.0 set to coldStart value
0x51efee4 (V main): TRIG"beta" dcOffset[ CH1 ] -1.6991698 set to coldStart value
Best regards
Hans
