Alternator noise when the alternator breaks

Alternator noise when the alternator is broken.
This is the sound that was in the drive recorder. During operation, the noise is just not heard only a little.
Before the alternator is broken, but it had been ringing at a frequency slightly higher,
Now lower frequency when the break. This change is also reflected in the engine sound, it was found that was broken even on the audibility during operation.
Because it is more or less power, perhaps one phase of the three-phase alternating current is assumed to have become bad.
Car Model: NISSAN CIMA Y31（1991）
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