Inspecting And Correcting The Alternator - Mitsubishi diesel engines Service Manual

ELECTRICAL SYSTEM - DISASSEMBLY, INSPECTION AND REASSEMBLY

2.2 Inspecting and correcting the alternator

Inspecting the diodes
(1)
Perform continuity test on each of the rectifier
diodes in the following manner.
Connect a tester between the diode lead
(a)
terminal and the casing of that diode. A great
resistance should be indicated in one direction
and a small resistance in the opposite
direction.
If the same level of resistance is indicated in
(b)
both directions, replace the rectifier. Perform
this test on all diodes.
Inspecting the field coils
(2)
Measure between the slip rings. Replace if no
(a)
continuity is indicated (open circuit).
Measure between the slip ring and the shaft (or
(b)
the core). Replace if continuity is indicated.
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Inspecting the diodes
Testing the field coils for open circuit
Testing the field coils for continuity