ESAB Migmaster 275, Instruction Manual

Page: 37 / 58

37
5.1 MaIntenance
Be sure the branch circuit or main disconnect switch is
off or electrical input circuit fuses are removed before
attempting any inspection or work on the inside of
the welding machine. placing the power switch on the
welding machine in the off position does not remove
all power from inside of the equipment.
Inspection, troubleshooting and repair of this equip-
ment may ordinarily be undertaken by a competent
individual having at least general experience in the
maintenance and repair of semi-conductor electronic
equipment. Maintenance or repair should not be under-
taken by anyone not having such qualifications.
Shut OFF shielding gas supply at source.
To aid in checking and servicing, use Schematic.
5.2 InspectIon anD serVIce
Keep Equipment in clean and safe operating condition free
of oil, grease, and (in electrical parts) liquid and metallic
particles which can cause short-circuits.
Regularly check cylinder valves, regulators, hoses, and gas
connections for leaks with soap solution.
Check for and tighten loose hardware including electrical
connection. Loose power connections overheat during
welding.
Immediately replace all worn or damaged power cables
and connectors. Check for frayed and cracked insulation,
particularly in areas where conductors enter Equipment.
The electrode wire and all metal parts in contact with it are
electrically energized while welding. Inspect these parts
periodically for defective insulation and other electrical
hazards.
If uninsulated cable and parts are not replaced, an arc
caused by a bared cable or part touching a grounded
surface may damage unprotected eyes or start a fire.
Body contact with a bared cable, connector, or uncovered
conductor can shock, possible fatally.
Keep power cables dry, free of oil and grease, and protected
at all times from damage by hot metal and sparks.
Clean dirt and metal particles from drive roll groove weekly;
replace roll if badly worn.
5.2.1 poWer source
5.2.1a rectIfIer
It is recommended that the rectifier be cleaned occasionally
by blowing it out with compressed air. This cleaning operation
is necessary so that maximum cooling will be accomplished
by the air stream. This should be done periodically, depend-
ing upon the location of the unit and the amount of dust
and dirt in the atmosphere.
The hermetically sealed silicon diode rectifiers are specially
designed for welding machine use and will not age or dete-
riorate in use. The four diodes are mounted on heat sinks. A
periodic cleaning of dust and dirt from these is necessary to
insure cooling of the rectifiers. Access is by removal of top
cover and side panels. Should any diode accidentally be
damaged and need replacement, it can be quickly removed
from the heat sink. The replacement diode should be of
the same type as the one removed, and should be locked
securely to the sink, preferably with a torque wrench set for
maximum of 25 ft. lbs. and a minimum of 20 ft. lbs. Exces-
sive torque will distort the mechanical structure and may
break the hermetic seal, whereas too little torque will result
in improper electrical connections.
5.2.1b fan Motor
All models are equipped with an exhaust fan and rely on
forced draft for adequate cooling for high duty cycles and
overloads. Lubricate the fan motor with a few drops of SAE-
20 non-detergent oil every three months.
sectIon 5 serVIce