I have a very strange issue that I can't explain but maybe someone can shed light.
I cut a homemade PCB on my CNC that basically just connects a couple Arduinos to a Raspberry Pi using i2c. It's mostly breakout board stuff. I actually have two variants of it that connect via a board connector. Both PCB's have the same issue:
There is a small voltage of exactly 0.37V on the circuit - EVEN when disconnected. But what even spookier is that the +5v voltage line for the Arduinos pull 2.7V even when there is no direct connection between the Raspberry Pi voltage powerline.
I thought first that I soldered a short circuit or something like that but I couldn't find anything - all traces are clean. I have a feeling that somehow there is some flux under the connectors for the Arduino and they short circuit some of the stuff.
But the 0.37V on both boards makes no sense... I tested with 3x different multi readers and they all show the same.
I know it's Halloween pretty soon but that's spooky.