TROUBLESHOOTING & REPAIR
F-42
F-42
RANGER 305D
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ROTOR RESISTANCE AND GROUND TEST (DYNAMIC)
(continued)
TEST PROCEDURE
This test requires that the brushes and slip rings
are clean, in good condition, and are properly
seated.
1. Perform the
brush and slip ring service
procedure
if necessary.
2. Insulate the lead wires that had been dis-
connected from the brushes during the static
rotor resistance test. Position and secure
them so the y cannot become damaged by
the spinning rotor.
3. Securely attach the ohmmeter leads to the
brush terminals. Use clips or terminals to
attach the leads
BEFORE
starting the
engine.
4. Start the engine and run it at high idle speed
(3650 RPM). The resistance should read
approximately 5* ohms at 77 degrees
Fahrenheit (25 deg. C.)
4. Shut off engine, and move one of the ohm-
meter leads to a good clean chassis ground.
5. Restart the engine and run it at high idle
speed (3650 RPM). The resistance should
be very high, at least 500,000 (500k) ohms.
6. If the resistance readings differ significantly
from the values indicated, re-check the
brushes and the brush spring tension. If the
brushes and slip rings are good, replace the
rotor.
7. If all testing is finished, perform the
Case
Cover Replacement
procedure.
*NOTE: The resistance of the windings will
change with temperature. Higher temperatures
will produce higher resistance, and lower tem-
peratures will produce lower resistance.
