Welding the wire connecting the diode, removing the diode, measuring and checking again to prove that the tube has now broken down. Replace the two new secondary tubes, connect the wires, and check whether the welding is strong. Step 4. Disconnect the main power switch, use a multimeter to prevent and measure four rectifier diodes, and find that there is a problem with two tubes.

1. Press the operating button of the grinding wheel motor to start the switch of the electric permanent magnet chuck. Note: the workpiece cannot be drawn, the contact of the relay is interlocked, and the grinding wheel motor cannot be started. 2, open the special distribution box of the machine tool, use the measuring pen to detect whether there is electricity at both ends of the fuse, and then use the multimeter 500V to measure the power supply voltage to 380V.