Lincoln Electric SVM194-A Shunt Field Coil Resistance and Ground Test, Shunt coil ground test

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F-46	TROUBLESHOOTING AND REPAIR			F-46
	SHUNT FIELD COIL RESISTANCE AND GROUND TEST
PROCEDURE		PROCEDURE (continued)
			Shunt coil ground test:
1.	Turn the engine off.
2. Open either or both of the doors on the			7. With the jumper plug or wire feed module
	machine.		unplugged from J5, measure the resistance
NOTE: Secure the doors in the open position using			between either the brown or blue wires and a
			good clean chassis ground. The resistance
the door restraint system. If the machine does not			should be very high, 500,000 (500k) Ohms min-
have a door restraint system, remove the doors or			imum.
securely restrain them to prevent them from falling			8. If the resistance is still lower than 500,000
closed.
Test the shunt coil resistance:			(500k) Ohms, check the shunt coil lead wires
			between the test points and the coils. Also
3.	Remove the jumper plug or wire feed module		check the lead wire connecting the two shunt
	harness plug from J5. Locate the brown and		coils together inside of the generator. Look for
	blue wires in J5, (pin numbers 3 and 5). Check		pinched wires and damaged insulation. If the
	the resistance between these two leads.		low resistance is determined to be between
	Resistance should measure about 59 ohms at		chassis wound and one of the shunt coils,
	77°F. (25° C.)		replace the coil set.
NOTE: It is always best to place probes in the lead			9. Reconnect the wires and replace any covers
	end of Molex connectors. Molex pins can		that have been removed.
	be easily damaged if probes are inserted in
	the connection pin end.		*NOTE: The resistance in the copper windings will
4. If the resistance reading is correct, proceed to
			change with temperature. Higher temperatures will
	the Shunt Field Coil Resistance and Ground
	Test		produce slightly higher resistance, and lower tem-
5.	If the resistance is significantly higher than 59*		peratures will produce slightly lower resistance.
	ohms, check the wiring between the test points
	and the shunt coils. Check the lead wire con-
	necting the two shunt coils together inside the
	generator frame. See the wiring diagram and
	the internal generator diagram. If these lead
	wires and connections are undamaged, one of
	the coils is likely open. Replace the shunt field
	coil set.

6. If the resistance is significantly lower than 59* Ohms, check the wiring between the test points and the coils for damaged insulation, pinched wires, etc. If the lead wires and insulation are in good condition, replace the shunt coil set.

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CLASSIC® 300D & 300G