I am debugging my PCB where a control signal unexpectedly drops from 5v to 1v, hence toggles the logic.
After power up, the signal is at 5.0v.
The interesting thing is when a tweezer or any metal probe touches that pin, the signal drops to 1.0v right away, not all the way to 0v though.
I wear gloves for insulation and hold the tweezer.
A more interesting one is when I put the tweezer aside, still wear gloves, power cycle the whole, and touch that pin with my finger, the signal stays at 5v and never changes.
I guess there might be short-circuit somewhere on the PCB, but two experiments confused me a lot.
The series resistance of the a tweezer, a glove, and my body are the sum of them, but the tweezer is nearly nothing.
Could EE veterans help me to brainstorm? Thank you