The observation sites generally located in open areas, and wind sensors are installed at the altitude of 10 meters, so it is easily damaged by lightning. The circuit diagram is drawn according to the wind direction sensor, and the working principles are analyzed. A gray code detection circuit is designed, which can conveniently and intuitively identify the failure bit in the 7 bit LEDs, so to find the reason and related components for failure. A simple method of replacing patch chips, in case of no special tool, is introduced, and some examples are given.