Lincoln Electric IM872 LF-74 WIRE FEEDER - Manual (Page 43)

E-3 TROUBLESHOOTING E-3
LF-74
Observe all Safety Guidelines detailed throughout this manual
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.
CAUTION
PROBLEMS
(SYMPTOMS)
POSSIBLE
CAUSE
RECOMMENDED
COURSE OF ACTION
Variable or "hunting" arc.
The motor thermal LED illuminates.
When the gun trigger is pulled, the drive
rolls spin but no arc is present.
The arc burns back to the tip at the end
of the weld.
The gas continues to flow for a long time
at the end of a weld.
1. Check for proper size contact Tip.
Make sure the contact tip is not worn,
free of spatter and not melted.
2. Clean and tighten all electrode and
work connections.
3. Verify the proper polarity is being
used for the weld procedure.
4. Make sure the proper electrode stick-
out is being maintained.
5. Check the gas flow rate and mixture.
6. Verify the gun bushing is tightly
mounted to the wire drive.
7. Verify the gun is tightly mounted to
the gun bushing.
1. Check for sharp bends in the gun
liner.
2. Examine the contact tip for wear and
proper size. Replace as necessary.
3. Check the gun liner. The welding
electrode should slide easily through
the gun.
4. Verify the proper gun liner is installed.
5. Reduce the pressure arm setting.
6. On bench models, make sure the
brake tension is not too tight.
7. If using a wire conduit, verify the wire
slides easily through the conduit.
1. Check all electrode and work connec-
tions.
2. Verify the gun bushing is tightly to the
wire drive.
3. Verify the gun is tightly mounted to
the gun bushing.
4. Check the control cable and connec-
tors for cuts. Verify that no pins are
broken or bent.
5. Possibly Defective Power Source
1. If the timer kit is installed, reduce the
amount of burnback time.
1. If the timer kit is installed, reduce the
amount of postflow time.
If all recommended possible areas of
misadjustment have been checked
and the problem persists, Contact
your local Lincoln Authorized
Field Service Facility.