Lincoln Electric SVM157-A service manual Welding Problems

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F-9	TROUBLESHOOTING AND REPAIR					F-9
Troubleshooting Guide – See Wiring Diagrams for location of specified					Observe Safety Guidelines
components and for troubleshooting of specific circuits.				detailed in the beginning of this manual.
PROBLEMS		POSSIBLE AREAS OF		RECOMMENDED
(SYMPTOMS)		MISADJUSTMENT(S)		COURSE OF ACTION
			WELDING PROBLEMS
Poor arc striking with electrode		1.	Make sure the settings for wire	1. The output capacitors may be faulty.
sticking or blasting off.			feed speed and voltage are cor-	Check for loose connections at the
			rect for the process being used.	capacitors.	Also	check for leaky
				capacitors. Replace if necessary.
		2.	Make certain the gas shielding is
			correct for the process being	WARNING: The liquid electrolyte in
			used.	these capacitors is toxic. Avoid con-
				tact with any portion of your body.
		3.	Make sure the machine’s recon-
			nect panel is configured properly	2. Perform the Output Diode Rectifier
			for the input voltage being	Test.
			applied.
The arc is unstable and or “hunting”		1.	Check for a worn or melted con-	1. Check for loose or faulty connections
			tact tip.	at the output terminals, choke, output
				capacitors,	output	selector switch,
		2.	Check for loose or faulty connec-	output contactor, and all heavy cur-
			tions on the work and gun cables.	rent carrying leads.		See the wiring
				diagram.
		3.	Make sure the electrode polarity
			is correct for the welding process	2. Check the output selector switch for
			being used.	proper operation and good connec-
				tions.
		4.	Check for rusted or dirty electrode
			wire.	3. The output capacitors may be faulty.
				Check for loose connections at the
		5.	Make sure the machine’s settings	capacitors.	Also	check for leaky
			and shielding gas are correct for	capacitors. Replace if necessary.
			the process being used .
				WARNING: The liquid electrolyte in
				these capacitors is toxic. Avoid con-
				tact with any portion of your body.
				4. Perform the Output Bridge Rectifier
				Test.

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact the Lincoln Electric Service Department for technical troubleshooting assistance before you proceed. Call 1-800-833-9353

POWER MIG 200