Alternator: Testing and Inspection

INSPECTION

Rotor:

ROTOR
1. Check rotor coil for continuity. Check to ensure that there is no continuity between slip rings. If resistance is too small, it means that there is a short circuit. If there is no continuity or if there is a short circuit, replace rotor assembly.
Resistance value: Approx. 3 - 5 Ohms
2. Check rotor coil for grounding. Check to ensure that there is no continuity between slip ring and core. If there is continuity, replace rotor assembly.

STATOR

Stator:

1. Make continuity test on stator coil. Check to ensure that there is continuity between coil leads. If there is no continuity, replace stator assembly.

Stator:

2. Check coil for grounding. Check to ensure that there is no continuity between coil and core. If there is continuity, replace stator assembly.

POWER DIODES
1. Apply the negative test probe of the diode tester or a multimeter with a diode test feature to the positive heatsink and the positive probe alternatively to A, B and C, a low resistance reading, or the forward voltage drop across the diode should be obtained. Reverse the test probes, a high resistance reading or a higher reverse voltage should be obtained.
2. Connect the positive test probe to the negative heatsink and the negative test probe alternatively to D, E and F, a low resistance of forward voltage drop across the diode should be obtained. Reverse the test probes, a high resistance reading or higher reverse voltage reading should be obtained.

BRUSHES
1. Ensure the brushes have not been worn to or beyond their wear limit,
Brush wear limit: 3.8 mm (0.15 in.)
2. Check the brush springs for burning and loss of tension due to excessive heat.

SLIP RINGS
1. Check the slip rings for excessive wear and damage.
Minimum slip ring diameter: 26.7 mm (1.05 in.)