Lincoln Electric R3R 500-I, R3R 375-I manual Troubleshooting

E-5		TROUBLESHOOTING			E-5
	Observe all Safety Guidelines detailed througout this manual
	PROBLEMS		POSSIBLE CAUSE		RECOMMENDED
	(SYMPTOMS)				COURSE OF ACTION
			FUNCTION PROBLEMS
H. Machine trips off when under no		1. Power bridge rectifier may have		1.	Refer to Power Hybrid,
load or makes excessive noise			a shorted diode or SCR.		Troubleshooting Procedures,
like it is loaded.					Section J and Snubber, Section
					F.
		2.	Short in the transformer.	2.	Repair.
		3.	Fan hitting vertical baffle.	3.	Clear the fan.
I. Variable or sluggish welding arc.		1. Poor work or electrode cable		1.	Check and clean cable connec-
			connection.		tions.
		2.	Current too low.	2.	Check recommended currents
					for rod type and size.
		3.	Welding leads too small.	3.	See Table in Output Connection
					Section.
		4.	Open SCR or diode in power	4.	Check per Power Rectifier
			rectifier bridge.		Bridge Troubleshooting
					Procedures, Section J and
					Snubber, Section F.
		5.	Control circuit problems.	5.	See SCR Troubleshooting,
					Section K.
J. Welder will not shut off.		1. Input contactor contacts frozen.		1.	Replace input contactor.
K. Current control on machine not		1. Current control switch in wrong		1.	Place switch in “machine” ( I )
functioning.			position.		position.
		2.	Current control switch defective.	2.	Check per Section H.
		3.	Current control potentiometer	3.	Check per Section G.
			defective.
		4.	Lead or connection in control	4. Repair or connect.
			circuit open.
		5.	Defective control or circuit	5.	See SCR Troubleshooting,
			boards.		Section K.

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact your Local Lincoln Authorized Field Service Facility for technical troubleshooting assistance before you proceed.

IDEALARC® R3R 375-I, 500-I AND 600-I