Positive Power Diodes Test; Negative Power Diodes Test; Rotor - New Holland TD60D Repair Manual

14 SECTION 55 - - ELECTRICAL SYSTEM - - CHAPTER 4

POSITIVE POWER DIODES TEST

Put an ohmmeter point in contact with the positive
(X) alternator terminal and the other successively
with each of the three terminals (A--B--C) (Fig. 21).
Repeat the three measurements after reversing the
instrument point connections.

NEGATIVE POWER DIODES TEST

Put an ohmmeter point in contact with the negative
(Y) diodes plate and the other successively with
each of the three terminals (A--B--C) (Fig. 22).
Repeat the three measurements after reversing the
instrument point connections.
In the three tests described above, the instrument
should show resistance at each terminal (A--B--C).
Reversing the instrument point connection, there
should be no resistance (Fig. 22). If there is resis-
tance in both cases, this means short--circuited
diodes. Otherwise, with a R=0 value (interrupted
diode), change the whole rectifier bridge.

ROTOR

CHECK ON ROTOR WINDING RESISTANCE
MEASURED BETWEEN PINS CONNECTED TO
BRUSHES
Disconnect the excitation diode terminal wire
connector (1) from the pin connected to the positive
brush. Put both points of an ohmmeter (regulated
on Ω x 1 scale) in contact with the two voltage
regulator--brush holder pins. If resistance reading is
different from the indicated value or if it shows
infinity (interrupted circuit), check and, if necessary,
change the rotor (Fig. 23).
603.54.471.00 - - 11 - - 2004
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