Lincoln Electric SVM 117-A service manual Perform the SCR Rectifier

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F-6	TROUBLESHOOTING & REPAIR					F-6
TROUBLESHOOTING GUIDE - Observe all Safety Guidelines detailed throughout this manual
PROBLEMS			POSSIBLE AREAS OF		RECOMMENDED
(SYMPTOMS)			MISADJUSTMENTS(S)		COURSE OF ACTION
			FUNCTION PROBLEMS
No control of arc voltage. Wire feed-		1.	The Arc Voltage Control poten-	1.	The Arc Voltage Control poten-
ing is normal.			tiometer may be dirty. Rotate		tiometer may be faulty. Check or
			several times and check if prob-		replace. See Wiring Diagram.
			lem is resolved.
				2.	Perform the SCR Rectifier
					Assembly Test.
				3.	The control board may be faulty.
					Replace.
There is no gas flow when gun trig-		1.	Check gas source and hoses for	1.	Check the gas solenoid by dis-
ger is pulled. Wire feeds and weld			leaks or kinks.		connecting it from the control
voltage is present.					board (Plug J8) and applying a
					12 VDC external supply to the
					gas solenoid. If the solenoid
					does NOT activate then it may
					be faulty. Replace.
				2.	The control broad may be faulty.
					Replace.
The machine stops feeding wire		1.	Check for mechanical restric-	1.	Check the motor armature cur-
while welding.			tions in the wire feeding path.		rent. Normal armature current is
			The gun may be clogged.		1.75 amps maximum. If the
					motor armature current is normal
					the control board may be faulty.
					Replace.
				2.	If the motor armature current is
					high (2 to 2.5 amps) and there
					are NO restrictions in the wire
					feeding path then the motor or
					gear box may be defective.
					Replace.

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, con- tact the Lincoln Electric Service Department for technical troubleshooting assistance before you proceed call 216- 383-2531 or 1-800-833-9353

WIRE-MATIC 250