Alternator: Testing and Inspection

WAVE PATTERN CHECK USING AN OSCILLOSCOPE




MEASUREMENT METHOD
Connect the oscilloscope special patterns pick-up to the generator "B" terminal

Standard Waveform:

NOTE: The voltage waveform of the generator "B" terminal can undulate as shown. This waveform is produced when the regulator operates according to fluctuations in the generator load (current), and is normal for the generator.

If the ripple height is abnormally high (approximately 2 V or more during idling), the wires between the generator "B" terminal and the battery have broken due to fuse blowing, etc. The generator is usually operating properly.

ABNORMAL WAVEFORMS EXAMPLES

NOTE: The size of the waveform patterns can differ greatly, depending on The adjustment of the variable knob on the oscilloscope.

NOTE: Identification of abnormal waveforms is easier when there is a large output current (regulator is not operating). (Waveforms can be observed when the headlights are illuminated.)

NOTE: Check the conditions of the charging indicator light (illuminated/not illuminated) also, and carry out a total check

Abnormal Waveforms: