Alternator: Testing and Inspection
GeneratorINSPECTION
1. DIODE
CAUTION: There is the possibility of damaging the diodes if a mega-tester (used to measure high voltages) or a similar measuring instrument is used. Never use a mega tester or equivalent for this test.
1. Check for continuity between the diode lead and terminal E or B. If continuity is not as shown in the table, replace the rectifier.
- At analog type tester
- At digital type tester
2. ROTOR
1. Inspect the slip rings for contamination or any roughness on the sliding surface. Repair the slip ring surface using a lathe or sand paper.
2. Measure the slip ring outer diameter. Replace the rotor if the slip ring is worn.
Slip ring outer diameter:
Standard
22.7 mm (0.894 in)
Limit
22.1 mm (0.870 in)
3. Using a circuit tester, check the resistance between slip rings. If resistance exceeds the standard, replace the rotor.
Standard:
Approx. 2.0 - 2.3 Ohms
4. Check the continuity between slip ring and rotor core or shaft. If there is continuity, replace the rotor because the rotor coil is grounded.
5. Check the bearings. If there is any noise, or the rotor does not rotate smoothly, replace the bearings.
3. STATOR COIL
1. Inspect the continuity between the stator coil terminals. If continuity is not as shown in the table, replace the stator coil.
2. Inspect the continuity between the stator coil stator core and lead wire terminals. If there is continuity, replace the stator coil because the stator coil is grounded.
4. BRUSH
1. Measure the length of each brush. Replace the brush if wear exceeds service limits. There is a service limit mark (A) on each brush.
Brush length:
Standard (1)
22.5 mm (0.886 in)
Limit (2)
5.0 mm (0.197 in)
2. Using a spring pressure indicator, push the brush into the brush holder until its tip protrudes 2 mm (0.08 in). Then measure the pressure of brush spring. If the pressure is 1.7 N (173 gf, 6.11 ozf) or less, replace the brush spring. 4.1 - 5.3 N (418 - 540 gf, 14.75 - 19.06 ozf) pressure is required on the new spring.
5. BALL BEARING
Check the ball bearings. Replace the ball bearings if there is resistance in the rotation, or if there is any abnormal noise.
6. OTHER INSPECTIONS
Check that the generator does not have deformation, cracks and any other damage.