Lincoln Electric LF-72/74 service manual Calibration Specification, Routine Maintenance

Models: LF-72/74

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D-2

MAINTENANCE

D-2

 

 

 

MAINTENANCE

CALIBRATION SPECIFICATION

 

WARNING

 

Safety Precautions

 

ELECTRIC SHOCK can kill.

 

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WARNING

ELECTRIC SHOCK can kill.

Do not touch electrically live parts such as output terminals or inter- nal wiring.

When inching with gun trigger, electrode and drive mechanism are “hot” to work and ground and could remain energized several seconds after the gun trigger is released.

Turn OFF input power at welding power source before installation or changing drive roll and/or guide tubes.

Welding power source must be connected to sys- tem ground per the National Electrical Code or any applicable local codes.

Only qualified personnel should perform mainte- nance work.

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Observe all additional Safety Guidelines detailed throughout this manual.

ROUTINE MAINTENANCE

Clean and tighten all weld terminals.

Inspect all weld cables, control cables, gun cables and shielding gas hoses. Repair or replace as nec- essary.

PERIODIC MAINTENANCE

Clean drive roll grooves.

Blow out or vacuum the inside of the feeder.

Do not touch electrically live parts.

When inching with the gun trigger, electrode, wire drive motor and drive mechanism are "hot" to work and ground and could remain energized several seconds after the gun trigger is released.

Welding power source must be connected to system ground per the National Electrical Code or any applicable local codes.

Only qualified personnel should perform mainte- nance work.

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Calibration of the LF-72 may be required when the p.c. board, potentiometer or motor is replaced or serviced. Calibration matches the scale on the name plate to the actual wire feed speed.

To verify if calibration is necessary:

1.Turn off power to the LF-72.

2.Assemble .045 drive rolls, inner guide and the outer guide into the drive. Remove the gun from the wire feeder if assembled.

3.Load .045 wire into the drive. Cut the wire flush with the end of the gun bushing.

4.Set the WFS knob to 300 ipm.

5.Using the COLD FEED switch, feed wire for 10 seconds.

6.Cut the wire flush with the end of the gun bushing. Measure the length of the wire. If the wire mea- sures 50 ± 2.5 inches then calibration is not required.

Tools required:

5/16" nut driver

3/4" open end wrench WFS meter or RPM meter

Shorting plug. The shorting plug shorts pins 1

&5 of connector J2 on the p.c. board. J2 is a

6 pin molex connector.

To calibrate the LF-72:

1.Turn off power to the LF-72.

2.Disconnect the electrode lead from the feedplate and from the welding power source.

3.Remove the 5 screws securing the wraparound. (The door is not shown for clarity. See Figure D.1”)

LF-72/74

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Lincoln Electric LF-72/74 service manual Calibration Specification, Routine Maintenance, Periodic Maintenance