Maintenance; Safety Precautions; Routine Maintenance; Circuit Protection And Automatic Shutdown - Lincoln Electric LN-25 Service Manual

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SAFETY PRECAUTIONS

WARNING
ELECTRIC SHOCK can kill.
• Do not operate with covers
removed.
• Turn off power source before
installing or servicing.
• Do not touch electrically hot
parts.
• Turn the input power to the
welding power source off at
the fuse box before working
in the terminal strip.
• Only
should install, use or service
this equipment.

ROUTINE MAINTENANCE

DRIVE ROLLS AND GUIDE TUBES
After feeding every coil of wire, inspect the drive roll
section. Clean it as necessary. Do not use a solvent
for cleaning the idle roll because it may wash the lu-
bricant out of the bearing. The drive roll, idle roll and
guide tubes are stamped with the wire sizes they will
feed. If a wire size other than that stamped on the rolls
is to be used, the rolls and guide tubes must be
changed.
The drive rolls for .045 and .052 cored electrode and
1 ⁄ , .068 and 5 ⁄ electrode have a double set of teeth
1 6 6 4
so they can be reversed for additional life. Between
the two knurled rolls (except
shim washer which limits the damage to the electrode
if wire feeding problems occur. Drive rolls for .023
through .052 solid electrode have no teeth.
See Wire Feed Drive Roll and Guide Tube Kits Sec-
tion for roll changing instructions.
WIRE REEL SPINDLE
No routine maintenance required. Do not lubricate
spindle.

MAINTENANCE

qualified personnel
1 ⁄ and smaller rolls) is a
1 6
CONTROL BOX
Every six months open and inspect the control sec-
tion. The accumulated dirt should be gently blown off
all of the electrical components. Be sure the air that
is being used is dry. Check that lead plugs are secure
in their receptacles.
WIRE DRIVE MOTOR AND GEARBOX
Every year examine the gearbox. Paint the gear teeth
with molydisulfide filled grease. Lincoln specification
E2322. Do not use a graphite grease.
Check the motor brushes. Replace if they are worn
down to 1 ⁄ '' or less. When ordering feed motor
4
b r u s h e s , g i v e a l l i n f o r m a t i o n f r o m t h e motor
nameplate.
GUN AND CABLE MAINTENANCE
See IM manual provided with the gun and cable as-
sembly.
CIRCUIT PROTECTION AND
AUTOMATIC SHUTDOWN
CONTROL PC BOARD FUSE
On G1757-6 (or higher part no.) PC boards the
fuse was replaced with electronic protection for trigger
circuit faults to electrode circuit.
On G1757-2 through -5 part no. PC boards, the
fuse interrupts the 500A lead to the trigger switch. On
G1757- 1 PC boards a 5 amp fuse was used to
interrupt the 667 lead. The LN-25 will not operate if
the fuse is blown.
AUTOMATIC PROTECTION SHUTDOWN
(See Automatic Protection Shutdown Section.)
ADJUSTING SPEED
SENSOR MODULE
The LN-25 Speed Sensor Module is a three lead Hall
Effect switch device encased in an externally threaded
housing which is screwed into a mounting plate on the
motor side of the wire drive gearbox.
Proper positioning of this module is critical to proper
operation of the LN-25 wire feed speed control. If the
LN-25
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1 ⁄ amp
8
1 ⁄ amp
8