What does it measure in differential mode if you shortcut AI+ AI- AIGND?
If you measure -.1V on the internal AIGND vs D-GND, can you do so with a external DMM? Pin 56 vs 53?
Visual inspection? maybe cleaning the board?
However that board disqualify for productive use IMHO.
Greetings from Germany
Henrik
LV since v3.1
“ground” is a convenient fantasy
'˙˙˙˙uıɐƃɐ lɐıp puɐ °06 ǝuoɥd ɹnoʎ uɹnʇ ǝsɐǝld 'ʎɹɐuıƃɐɯı sı pǝlɐıp ǝʌɐɥ noʎ ɹǝqɯnu ǝɥʇ'
