(1) What is the problem with one of the four rectifier diodes.
(2) There is carbon powder between the rotor and the motor commutator or the motor carbon brush itself is not good. Adhering to the maintenance standard with a definite purpose, the variable resistance is measured accurately first, and the resistance value changes periodically with the adjustment, confirming the resistance The thyristor is good, and no problem can be found by measuring the thyristor accurately, because the diode is a high-current gold-sealed tube, one end is screwed on the circuit board, and the other end is welded to the circuit board by wire wrapping and electric welding, and is removed from the circuit board. When it came down, it was found that the positive and negative are loose, and then shake it while accurately measuring, and confirm that the diode is intermittent.
(3) There are many occurrences of thyristors, generally penetrating short-circuit faults, leading the way, not being able to open or poor internal contact.
(4) Variable resistance. Because the variable resistance is installed on the operation panel, the vertical centrifugal fan has a particularly high frequency of application, and the looseness is very common after a long time.
