The electromagnet does not pick up, and the cause of this failure is mostly the internal fault of the main unit, the electromagnet coil is blown, and the line is interrupted. The solution is: first check whether there is a problem inside or outside the host; secondly, check Solenoid fuse, check whether the electromagnet has signs of energization, eliminate the mechanical jam, and detect the internal power supply when everything is normal; the common cause of this fault in the weighing packaging machine is: sensor damage, The bridge voltage is faulty, the line connection or interruption is wrong. The method of elimination is: detecting the load signal of the sensor and the connection or the host, and detecting the bridge and the amplifying circuit or the computer output display circuit, sometimes the system stability occurs. It is not good to cause the bag to be unstable. Solve this problem to test whether the line is faulty, or remove the host, apply a clear signal through the internal short circuit, determine whether the fault is in the machine or from the switch, and then solve the problem.