Troubleshooting - Miller Maxstar 140 Owner's Manual

4-3. Troubleshooting

Trouble
No weld output; unit completely inop-
erative; Ready light Off.
No weld output; Ready light On; Over-
Temperature light Off.
No weld output; Ready light On; Over-
Temperature light On.
No weld output; Ready light On; Over-
Temperature light Flashing.
Erratic or improper welding arc or out-
put.
Fan not operating (unit is equipped
with Fan-On-Demand so fan runs only
when needed).
Stick welding problems: Hard starts;
poor welding characteristcs; unusual poor welding characteristcs; unusual
spattering problems.
TIG welding problems: Wandering arc;
hard starts; poor welding character- hard starts; poor welding character-
istcs; spattering problems.
TIG welding problems: Tungsten elec-
trode oxidizing and not remaining bright trode oxidizing and not remaining bright
after conclusion of weld.
OM-2224 Page 20
Place line disconnect switch for circuit powering welder in On position.
Check and replace line fuse(s), if necessary, or reset circuit breaker.
Be sure input power cord is plugged in and that receptacle is receiving input power.
Check and secure loose weld cable(s) into receptacle(s) on welding power source.
Check and correct poor connection of work clamp to workpiece.
Unit overheated causing thermal shutdown. Allow unit to cool with fan On (see Section 2-5).
Reduce duty cycle or amperage to prevent further overload conditions.
Check and correct blocked/poor airflow to and around unit or move unit clear of blockages (see
Section 2-7).
Check and clean dirty power module (see Section 4-2).
Turn Power Switch Off and back On again. If light continues to flash, call or take machine to Facto-
ry Authorized Service Agent (this condition may indicate a fault in the power section).
Use proper size and type of weld cable (see your Distributer).
Clean and tighten all weld connections.
Check and reverse electrode polarity; check and correct poor connections to workpiece.
Unit is cool and not warmed up enough to require fan cooling.
Check for and remove anything blocking fan movement.
Have Factory Authorized Service Agent check fan motor and control circuitry.
Use proper type and size of electrode.
Use method shown in Section 8 to get better starts.
Check and reverse electrode polarity; check and correct poor connections to workpiece.
Use proper type and size of tungsten.
Use properly prepared tungsten.
Check and reverse electrode polarity; check and correct poor connections to workpiece.
Shield weld zone from drafts.
Check shielding gas supply, and be sure it is the correct type (argon) and that the cylinder is not empty.
Check and tighten all gas fittings.
Check and change electrode polarity; move Changeover Switch to TIG position.
Remedy