If there is a voltage difference between the power source connected to the barrel power input and the voltage specification of the device connected to the 4-pin interface (e.g. 24V barrel vs. 12V 4-pin or 5V barrel vs. 12V 4-pin), please modify the NA-EC1 input cable by cutting the yellow (power) pin of the cable to make sure that the lower voltage device will not be damaged by the higher voltage.