Checking the rotor
1. Check the rotor winding for damage. Check the resistance between the generator rings.
If the resistance is low, then there is a short circuit in the rotor (short circuit). If there is no connection, then the rotor winding is broken.
Resistance value: approximately 3.1 ohms.
2. Check the rotor winding for a short circuit to the housing. If the rotor winding is shorted to the magnetic circuit, then the rotor should be replaced.
Stator check
1. Measure the resistance between the stator winding terminals as shown in the figure below. If a winding break is detected, the stator should be replaced.
2. Measure the resistance between the terminals of the stator phase windings and the magnetic circuit, as shown in the figure below. If a short circuit of the phase windings to the magnetic circuit is detected, the stator should be replaced.
Checking the rectifier unit
1. Check the resistance between the positive plate of the heat sink and each of the stator winding connection points. If the "continuity" is carried out in both directions, then the corresponding diode is "broken". Replace the rectifier unit.
2. Check the resistance between the (-) heat sink plate and each of the stator winding connection points. If the "continuity" is carried out in both directions, then the corresponding diode is "broken". Replace the rectifier unit.
3. Check the condition of the three diodes. To do this, measure the resistance of each diode in the forward and reverse directions one by one. If the diode "rings" in both directions or "does not ring" in either direction, then such a diode is defective. If any of the diodes is defective, replace the rectifier unit.
Checking the brushes
1. Measure the brush protrusion as shown in the figure below. If the brush protrusion is less than 2 mm, the brush should be replaced.
2. Unsolder the connecting wire. Remove the old brushes.
3. Install new brushes into the brush holder as shown in the figure and solder the connecting wires.