Connecting the grounds together between the terminal board and the laptop fixed the voltage issue. However, the TC-08 will not produce any believable values from the pressure sensor. I put in the calibration data from the sensor manufacturer (Omega), which the output signal is ±50mV, and selected th...

3V AC are measured between the supply negative and the laptop case ground.

Is there a way to get rid of this voltage between the two without relying on battery power only on the laptop?

Thanks

I have not measured AC voltage, will try that next.

I have a similar issue, using a Pico Terminal Board for a pressure sensor connected to a TC-08 with 4 thermocouples also connected. The pressure sensor output is errant and unsteady, and intermittently causes cross talk with the thermocouples. - If the 5V power supply to the pressure sensor is unplu...