I am getting this same issue after just replacing everything related to the pt100. I was using this setup for years with no issues. I finished replacing the ramps board, amplifier board, heater cartridge, and pt100 sensor. During the first layer temperature will drop to zero then back which decouples the heater.
Did you ever resolve if your issue was a broken cable or not? I replaced the cable and changed the pin from A3 to A4 and updated the firmware and still getting the same issue. As soon as the print starts temperature goes to zero and fails.
Comments
Did you ever resolve if your issue was a broken cable or not? I replaced the cable and changed the pin from A3 to A4 and updated the firmware and still getting the same issue. As soon as the print starts temperature goes to zero and fails.