Rectifier Diode / Bridge: Testing and Inspection

AR15.40-P-9301-02TI Test diodes of alternator

Commercially available tools:

Connection schematic between battery and alternator:

In this test, it is not possible to assess the exciter diodes.

1 Connect the engine tester with oscilloscope (030).
2 Start engine.
3 Switch on low beam.
4 Assess diode harmonics at 3000 rpm (engine speed).

Shown on the oscilloscope - diode harmonics OK:

Diode harmonics in order (voltage spikes possible, but not significant) (example).

Shown on the oscilloscope - diode harmonics OK

Shown on the oscilloscope - positive diodes harmonics not OK:

One of the positive diodes is defective (example).

Shown on the oscilloscope - positive diodes harmonics not OK

Shown on the oscilloscope - negative diodes harmonics not OK:

One of the negative diodes is defective (example).

Shown on the oscilloscope - negative diodes harmonics not OK