Lincoln Electric SVM144-B service manual Welding Problems

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F-9	TROUBLESHOOTING & REPAIR					F-9
TROUBLESHOOTING GUIDE			Observe Safety Guidelines
		detailed in the beginning of this manual.
PROBLEMS		POSSIBLE AREAS OF	RECOMMENDED
(SYMPTOMS)		MISADJUSTMENT(S)	COURSE OF ACTION
		WELDING PROBLEMS
The arc is unstable and or “hunting”.		1. Check for worn or melted con-	1. Check for loose connections at
		tact tip.	the	output	terminals, the
			chokes, the capacitor bank and
		2. Check for loose or faulty con-	all heavy current carrying leads.
		nections on the work and elec-	See Wiring Diagram.
		trode cables.	2. Make sure that the transformer
		3. Make sure electrode polarity or	secondary leads			are securely
		welding process being used, is	connected to the SCR rectifier
		correct.	assembly.
		4. Check for rusty or dirty wire.	3. The output capacitor bank may
			be faulty. Check for loose con-
		5. Make sure machine settings and	nections at the capacitors. Also
		gas are correct for process	check	for	leaky	capacitors.
		being used.	Replace if necessary.
			WARNING: The liquid elec-
			trolyte in these capacitors is
			toxic. Avoid contact with any
			portion of your body.
			4. Perform the SCR Rectifier
			Assembly Tests.
			5. The control board may be faulty.
			Replace.
Weld bead is narrow or ropy. May		1. Make sure the weld procedure	1. The output capacitor bank may
have porosity with electrode stub-		and electrode polarity is correct	be faulty. Check for loose con-
bing into plate.		for the process being used.	nections at the capacitors. Also
			check	for	leaky	capacitors.
		2. Make sure shielding gas is cor-	Replace if necessary.
		rect and flow is proper.	WARNING: The liquid elec-
		3. Make sure the weld joint is not	trolyte in these capacitors is
		“contaminated”.	toxic. Avoid contact with any
			portion of your body.
			2. The control board may be faulty.
			Replace.

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con- tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.

POWER MIG 255