An oscilloscope shows the alternator’s output waveform, revealing diode and stator faults. MSG Equipment explains the method’s benefits and limits.
According to MSG Equipment, using an oscilloscope when testing an alternator lets technicians visually analyse the amplitude and shape of the output voltage. Failed or broken diodes in the rectifier bridge and stator winding shorts cause large ripple (a high AC component), so an oscilloscope is effective at detecting them.
The method has its difficulties: obtaining a stable waveform and interpreting it correctly takes experience, and oscilloscope checks are not suitable for every alternator or vehicle.
That is why workshops prefer professional test benches. The article cites the MS006, which has a built-in oscilloscope and can print results, and the MS002 COM, which tests 12 V alternators at up to 200 A.