Lincoln Electric SAE-300 HE Service Manual page 36

LINCOLN ELECTRIC
seated. Perform the Brush and Slip Ring Service Procedure (Exciter / Auxiliary Power Alternator), if
necessary.
7. Insulate the lead wires that had been disconnected from the brushes during the static rotor
resistance test. Position and secure them so they cannot become damaged by the spinning rotor.
It is recommended that the ohmmeter leads be securely attached to the brush terminals, using clips
or terminals BEFORE starting the engine. See Figure F.9.
8. Start the engine and run it at high idle speed (1800 RPM). The resistance should read approximately
40 ohms* at 77 deg. F. (25 deg. C).
9. Shut off engine and move one of the ohmmeter leads to a good clean chassis ground connection.
10. Restart the engine and run it at high idle speed (1800 RPM). The resistance should be very high, at
least 500,000 (500k) ohms.
11. 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.
12. When testing is complete, securely connect the leads to the brush terminals, replace the alternator
cover and close the left and right side covers. See Wiring Diagram.
*NOTE: The resistance of the copper windings will change with temperature. Higher temperatures
will produce higher resistance and lower temperatures will produce lower resistance.
Figure F.9 – Slip ring locations
SAE-300® HE Service Manual
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