Miller Bobcat 225 Owner's Manual page 78

13-16. Troubleshooting Guide For Semiautomatic Welding Equipment
Problem
Wire feed motor operates, but wire does not
feed.
Wire curling up in front of the wire feed rolls
(bird nesting).
Wire feeds, but no gas flows (GMAW).
Welding arc not stable.
OM-286503 Page 74
Probable Cause
Too little pressure on wire feed rolls.
Incorrect wire feed rolls.
Wire spool brake pressure too high.
Restriction in the gun and/or assembly.
Too much pressure on wire feed rolls.
Incorrect cable liner or gun contact tip size.
Gun end not inserted into drive housing
properly.
Dirty or damaged (kinked) liner.
Gas cylinder empty.
Gas nozzle plugged.
Gas cylinder valve not open or flowmeter not
adjusted.
Restriction in gas line.
Loose or broken wires to gas solenoid.
Gas solenoid valve not operating.
Incorrect primary voltage connected to weld-
ing power source.
Wire slipping in drive rolls.
Wrong size gun liner or contact tip.
Incorrect voltage setting for selected wire
feed speed on welding power source.
Loose connections at the gun weld cable or
work cable.
Gun in poor shape or loose connection inside
gun.
Remedy
Increase pressure setting on wire feed rolls.
Check size stamped on wire feed rolls, re-
place to match wire size and type if
necessary.
Decrease brake pressure on wire spool.
Check and replace cable, gun, and contact
tip if damaged. Check size of contact tip and
cable liner, replace if necessary.
Decrease pressure setting on wire feed rolls.
Check size of contact tip and check cable lin-
er length and diameter, replace if necessary.
Loosen gun securing bolt in drive housing
and push gun end into housing just enough
so it does not touch wire feed rolls.
Replace liner.
Replace empty gas cylinder.
Clean or replace gas nozzle.
Open gas valve at cylinder and adjust flow
rate.
Check gas hose between flowmeter and wire
feeder, and gas hose in gun and cable
assembly.
Have Factory Authorized Service Agent re-
pair wiring.
Have Factory Authorized Service Agent re-
place gas solenoid valve.
Check primary voltage and relink welding
power source for correct voltage.
Adjust pressure setting on wire feed rolls. Re-
place worn drive rolls if necessary.
Match liner and contact tip to wire size and
type.
Readjust welding parameters.
Check and tighten all connections.
Repair or replace gun as necessary.