Lincoln Electric SVM157-A service manual Tachometer Feedback Test

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F-8	TROUBLESHOOTING AND REPAIR					F-8
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
		WIRE FEEDING PROBLEMS
Rough wire feeding or the wire will		1. The gun cable may be kinked or
not feed but the drive rolls are turn-		twisted.
ing.		2. Check the drive roll tension and
		the position of the grooves.
		3. Electrode may be rusted or dirty.
		4. The contact tip may be damaged
		or not the correct size.
		5. Check the wire spindle for ease of
		rotation.
		6. Make certain the gun is pushed all
		the way into the gun mount and
		properly seated.
No control of wire feed speed.		1. The wire feed speed control may	1. The wire speed control potentiometer
Other machine functions are nor-		be dirty. Rotate several times and	may be	faulty.	Check or	replace.
mal.		check if the problem is resolved.	Normal	potentiometer resistance is
			10K ohms.
			2. Perform the Wire Drive Motor and
			Tachometer Feedback Test.
			3. The control board may be faulty.
There is no wire feed when the gun		1. Check for adequate wire supply.	1. Perform the Wire Drive Motor and
trigger is activated.	Normal open		Tachometer Feedback Test.
circuit weld voltage is present and		2. If the drive rolls are turning, check
the gas solenoid functions normally.		for a mechanical restriction in the	2. The wire speed control potentiometer
		wire feed path.	may be	faulty.	Check or	replace.
			Normal	potentiometer resistance is
		3. The gun liner may be clogged.	10K ohms.
		Check or replace.
			3. The control board may be faulty.
		4. If the drive rolls are not turning
		when the gun trigger is activated,
		contact your local Lincoln Electric
		Authorized Field Service Facility.

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