Dc motor controller is in use, can appear sometimes cannot be started, is this why? Below small make up to answer it. 1. Power loss, such as a power switch not good, the front-end fuse fusing, motor controller of main circuit and control circuit fuse fusing, the processing method is used to level the main circuit and control circuit fuse to the motor controller gradually inspections on each part of the wire and components, so as to find out the reason and repair. 2. Motor controller failure, such as brush wear serious, jam, spring pressure is not enough makes brush and commutator poor contact, such as processing method is to disconnect the power supply, using a multimeter resistance check the contact resistance between brush and commutator segment, and then find the breakpoint to repair. 3. Mechanical failure, such as motor controller with mechanical equipment or actuator stuck, starting under the heavy load, the processing method is to remove the power supply, to find and repair mechanical failure. To sum up, for the cause of the dc motor controller cannot be started, you know?