Why does the magnetic lock lose its magnetism? What should I do if the magnetic lock loses its magnetism?

The so-called magnetic lock uses the principle of electromagnetism. Do you know what happens when the magnetic lock loses its magnetism? The reason why the magnetic lock loses its magnetism is that the strong suction force becomes weaker and cannot work. So what should I do after losing its magnetism?

After finding that the magnetic suction cup has no magnetism, the first thing to do is to press the grinding wheel motor button and start the magnetic suction cup switch. The workpiece cannot be attracted because the contacts of the relay are interlocked and the grinding wheel motor cannot be started. Open the tool box, use a test pen to test the electricity at both ends of the fuse, and then use the multimeter AC 500V gear to measure the power supply voltage to 380V. Disconnect the main power switch, check whether the AC contactor has mechanical jamming, remove one of the contactor coil wires, and use the multimeter resistance to measure the resistance at both ends of the coil. The needle indicates normal, which proves that the coil of the magnetic suction cup is good.

Connect the coil wire of the magnetic suction cup, remove the undervoltage relay housing, measure the resistance at both ends of the coil, and the needle still indicates normal, indicating that the undervoltage relay coil is not broken, and then check whether the relay has mechanical jamming. Then turn on the upper power switch, use the multimeter AC gear to measure the transformer secondary voltage of 135 V, switch to DC gear to measure the voltage across the rectifier diode. Under normal circumstances, the DC voltage output by the bridge rectifier should be 110V. At this moment, there is no voltage output. Disconnect the main power switch, use the multimeter resistance to measure the four rectifier diodes respectively, and find that two of them have problems. Solder the wires connecting the diodes, remove the diodes, and measure and check again, which proves that the tubes have been broken down. Replace two new diodes, connect the wires, and check whether the welding is strong.