a、 The thyristor corresponding to the secondary pressure regulator is damaged, replace the secondary pressure regulator.
b、 If the actuator is faulty, check if it is damaged. For actuators controlled by forward and reverse signals, the following methods can be used: first disconnect the power supply, adjust the valve position to the middle position, connect the power supply to the actuator, and use a wire with a good insulation shell to power the reverse terminal of the actuator (i.e. the reverse terminal is connected to the phase wire), then the actuator will reverse (when the valve is reverse installed, it is forward), then disconnect the power supply to the reverse terminal, and power the forward terminal of the actuator (i.e. the forward terminal is connected to the phase wire)