CHARGING SYSTEM
SERVICE MANUAL NUMBER 23
Page 4C-20
90-861326--1 MARCH 1999
Component Testing
ROTOR
1. Test rotor field circuit for opens, shorts or high resistance (Test 1), using an ohmmeter
(set on R x1 scale), as follows:
72831
a
b
Testing Rotor Field Circuit
a -
Test 1
b -
Test 2
a. Connect one ohmmeter lead to each slip ring.
b. Ohmmeter reading should be 4.2 to 5.5 ohms with rotor at room temperature
70-80
°
F (21-26
°
C).
c. If reading is high or infinite (no meter movement), high resistance or an open exists
in the field circuit. Check for poor connections between field winding leads and slip
ring terminals. If cause for open or high resistance cannot be found, connect ohm-
meter directly to slip ring terminals. If correct reading is now obtained, or if reading
is still high or infinite, replace complete rotor assembly.
d. If reading is low, a short exists in the field circuit. Inspect slip rings to be sure that
they are not bent and touching outer slip ring. Also, be sure that excess solder is not
shorting terminals to aft slip ring. If cause for short cannot be found, unsolder field
winding leads from slip ring terminals and connect ohmmeter directly to leads. If
correct reading is now obtained, or if reading is still low, slip rings and rotor field
windings are shorted, and complete rotor assembly must be replaced.
73112
b
a
c
d
a -
Field Winding Leads
b -
Slip Rings
c -
Rotor Shaft
d -
Pole Pieces
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