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OM-2031
(d) Checking the Actuator
The actuator does not require any adjustments. An actuator malfunction, when it occurs, will
result in the actuator being totally inoperative, either due to the actuator coil being open or
shorted to the actuator case. Resistance measurements will reveal either of these conditions.
(4) Checking Magnetic Pick-up signal
Connect a high impedance voltmeter to magnetic pickup input terminals (10 and 11, Fig. 6) on control-
ler terminal board. The voltage value at no load, governed speed should be 4-V AC MINIMUM.
NOTE: A signal as low as 2.5-V is sufficient to operate the control unit satisfactorily. If a no-voltage
condition is indicated, the magnetic pick-up is too far away from flywheel teeth, or it is defective.
5. Generator and Exciter Test
The generator fields may be tested with a "Kelvin" bridge. This is a double-bridge type instrument required
for the very low resistances encountered in this test. It is understood that 0 resistance indicates a SHORT
CIRCUITED condition. An infinite resistance reading indicates an OPEN CIRCUITED condition. See Fig.
7 below for resistance values.
NOTE: The equipment should be COLD or at normal ambient temperature when tests are made.
A. Disconnect generator stator leads at the power module panel.
B. Disconnect exciter leads from terminal board mounted on rear of engine control panel. Positive
lead is RED Negative lead is YELLOW-BLACK.
C. Check resistances and compare to values given in Fig. 7.
TEST CONNECTION
GENERATOR STATOR
Phase A to N
Phase B to N
Phase C to N
NOTE: The two leads of a phase must be connected when test is made.
EXCITER A-B, B-C, A-C
Field (RED to YELLOW-BLACK)
2-3
Page 16
NOMINAL RESISTANCE IN OHMS
Generator and Exciter Stator Test Values
(70F Ambient Temperature)
Figure 7
0.00827
0.00835
0.00840
0.1
7.23
August 5/89 Revised
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