Troubleshooting - Miller Maxstar 91 Manuel Du Propriétaire

5-3. Troubleshooting

Trouble
No weld output; unit completely inop-
erative.
No weld output; fan motor FM running
and pilot light on.
Low weld output with no control.
Limited output and low open-circuit
voltage.
Erratic or improper weld output.
Arc not forming when using Lift-Arc.
Fan motor does not run.
Wandering arc; poor control of arc di-
rection.
Tungsten electrode oxidizing and not
remaining bright after conclusion of
weld.
Be sure Power switch is On.
Secure power cord plug in receptacle (see Section 3-7).
Check line fuse(s), and replace if needed. Reset circuit breakers (see Section 3-7).
Check for proper input connections (see Section 3-7).
Check position of Output (Contactor) switch (see Section 4-2).
Thermostat TP1 open (overheating). Allow fan to run; thermostat closes when unit has cooled (see
Section 2-2).
Check position of Amperage Control switch (see Section 4-3).
Have Factory Authorized Service Agent check control board PC1.
Check incoming power for correct voltage. Replace line fuse if open or reset circuit breaker (see Sec-
tion 3-7).
Check for proper input and output connections (see Sections 3-2, 3-4, and 3-7).
Tighten all welding cable connections (see Sections 3-2 and 3-4).
Check for proper size and type of cable (see Section 3-2).
Check for proper input and output connections (see Sections 3-2, 3-4, and 3-7).
Replace electrode (see Section 7).
Check electrode and workpiece, clean as needed to allow good contact.
Have Factory Authorized Service Agent check fan motor FM.
Reduce gas flow rate.
Select proper size tungsten (see Section 7-1).
Properly prepare tungsten (see Sections 7-2 and 7-3).
Shield weld zone from drafts.
Increase postflow time.
Check and tighten all gas fittings.
Water in torch. Refer to torch Owner's Manual for part(s) requiring replacement, and repair torch as
necessary.
Remedy
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