ALTERNATOR ASSEMBLY MAINTENANCE (152 HP) - CONTINUED
To test diode trio (18), connect ohmmeter between
diode trio single connector (44) and each of the other
connectors (45 thru 47) in turn. Observe resistance
reading on ohmmeter.
Reverse ohmmeter leads, or reverse meter polarity and
repeat step 3 above.
At one polarity, resistance reading should be low and
at the other polarity, resistance reading should be very
high, if diodes are good.
If both readings on same set of connectors are either
high or low, the associated diode is faulty and entire
diode trio must be replaced.
To test rectifier bridge (23), connect ohmmeter from grounded heat sink (48) to diode terminal (49) and note resistance
Reverse ohmmeter leads or reverse meter polarity and again note resistance reading.
At one polarity, resistance reading should be low and at the other polarity, resistance reading should be very high, if
diode is good. If diode if faulty, both readings will be either low or high.
Repeat above sequence between grounded heat sink
(48) and diode terminals (50 and 51), and then
between insulated heat sink (52) and each diode termi-
nal (49 thru 51).
If any set of readings indicates a faulty diode, replace
complete rectifier bridge (23).
To test rotor (7) for short or open circuits, connect
ohmmeter between slip rings (53), in turn, and rotor
shaft (54) (connection A). Observe resistance reading
Resistance reading should be high (infinite). If not, rotor (7) is defective and must be replaced.
Connect ohmmeter leads across slip rings (53) (connection B). Observe resistance reading on ohmmeter.
A high (infinite) resistance reading indicates an open rotor winding and rotor (7) must be replaced.