The following methods can usually be used to measure the quality of a DC motor:
Resistance measurement method: Set the multimeter to the resistance position and measure the resistance value between the two terminals of the DC motor. If the resistance value is zero or infinite, it indicates that the DC motor may be damaged.
Voltage measurement method: Connect the positive pole of the DC power supply to the positive pole of the DC motor, and connect the negative pole to the negative pole of the DC motor. Use a multimeter to measure the voltage between the two terminals of the DC motor. If the voltage value is zero, it indicates that the DC motor may be damaged.
Rotation measurement method: Rotate the rotor of the DC motor by hand to check for any jamming or excessive friction. If these problems occur, repair or replacement of components is necessary.
It should be noted that when conducting DC motor measurements, the power supply needs to be disconnected and safety ensured. If you are not familiar with motor maintenance operations, it is recommended to seek professional assistance.