Lincoln Electric FLEX FEED 74 HT Operator's Manual page 53

FLEX FEED™ 74 HT
PROBLEMS
(SYMPTOMS)
Wire feed speed consistently oper-
ates at the wrong value. The speed
changes when the wire feed speed
knob is adjusted.
The wire feed speed stuck at 200-
300 in/min and there is no change
when the wire feed speed knob is
adjusted.
Variable or "hunting" arc.
The wire drive feeds wire at the cor-
rect speed but there is not welding
output.
There is gas flow but the feeder
does not feed wire
Poor arc starts with sticking or
"blast-offs", weld porosity, narrow
and ropy looking bead.
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.
Observe all Safety Guidelines detailed throughout this manual
POSSIBLE AREAS OF
MISADJUSTMENTS(S)
1. The jumper lead 20 tooth/30 tooth
pinion gear is connected improp-
erly.
2. The wrong gear is installed in the
wire drive.
3. The wrong decal was placed on
the case front.
4. The brushes on the motor are
worn.
1. The tachometer is connected
improperly.
2. The tachometer has failed.
1. Wrong size, worn and/or melted
contact tip
2. Worn work cable or poor work
connection.
3. Wrong polarity.
4. The gas nozzle is extended
beyond the contact tip or the wire
stickout is too long.
5. Poor gas shielding on processes
requiring gas.
1. If a gouging kit is installed, the
gouging switch is in the "gouge"
position
2. If a gouging kit in installed, verify
there is continuity from the elec-
trode input to the wire drive.
1. If the advanced user interface is
installed, verify the preflow time
has not been set to a high value
1. Improper procedures or tech-
niques.
CAUTION
E-3
TROUBLE SHOOTING
RECOMMENDED
COURSE OF ACTION
1. Properly connect the jumper lead
in the harness..
2. Install the proper pinion gear in
the wire drive.
3. Place the correct WFS decal on
the case front.
4. Inspect and replace the motor
brushes.
1. Verify all of the tachometer leads
are properly connected.
2. Replace the motor and tachome-
ter assembly.
1. Replace the contact tip.
2. Verify all work and electrode con-
nections are tight and that the
cables are in good condition.
Clean/replace as necessary.
3. Adjust the polarity to match the
process.
4. Adjust the gas nozzle and shorten
the stickout to ½ to ¾ inches.
5. Check gas flow and mixture.
Remove or block sources of
drafts.
1. Place the rocker switch in the
welding position.
2. Repair loose connections.
Replace the contactor.
1. Adjust the preflow timer for a
shorter amount of time.
1. See "Gas Metal Arc Welding
Guide" (GS-100)