Use a multimeter to check whether the brushes of the DC motor are in the neutral position

The specific method of using the induction method and a multimeter to detect whether the brushes of a DC motor are in the neutral line position is as follows.

(1) Connect the detection circuit. When the armature is in a static state, connect the multimeter (set to the milliampere range) to the two adjacent brushes of the DC motor, and connect the excitation winding to a 1.5-3V DC power supply
(dry batteries can be used) through a switch, as shown in Figures 9-11.

(2) Detection method. Alternately close or open the SA1 switch. If the multimeter pointer swings left and right, it means that the brush position is incorrect. In this case, loosen the brush holder, move the brush holder in the forward and reverse directions, and adjust the position of the brush until the multimeter pointer no longer moves left and right when closing or opening SA1. At this time, the brush is in the neutral line position.