Lincoln Electric LF-72/74 User Manual

LF-72/74
SVM171-A
January, 2007
Safety Depends on You
Lincoln arc welding and cutting
equipment is designed and built
with safety in mind. However,
your overall safety can be
increased by proper installation
. . . and thoughtful operation on
your part.
DO NOT INSTALL,
OPERATE OR REPAIR THIS
EQUIPMENT WITHOUT READ-
ING THIS MANUAL AND THE
SAFETY PRECAUTIONS CON-
TAINED THROUGHOUT.
And,
most importantly, think before
you act and be careful.
SERVICE MANUAL
For use with machines having Code Number : 11075 thru 11293
Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC
View Safety Info View Safety Info View Safety Info View Safety Info
• Sales and Service through Subsidiaries and Distributors Worldwide •
Cleveland, Ohio 44117-1199 U.S.A. TEL: 1-888-935-3877 FAX: 216.486.1751 WEB SITE: www.lincolnelectric.com
• World's Leader in Welding and Cutting Products •
Copyright © 2007 Lincoln Global Inc.

Lincoln Electric LF-72/74 Specifications

General

Brand	Lincoln Electric
Model	LF-72/74
Category	Welding System
Language	English

Summary

SVM171-A LF-72/74 Service Manual

Safety First: Your Responsibility

Emphasizes user responsibility for safe installation and operation.

Comprehensive Safety Precautions

Electrical Shock and Arc Hazards

Highlights dangers of electrical shock and arc rays, advising protective measures.

Fumes, Gases, and Fire Prevention

Warns about welding fumes, gases, fire, and explosion risks.

Compressed Gas Cylinder Safety

Safety precautions for handling compressed gas cylinders.

LF-72 Maintenance Procedures

LF-74 Maintenance Procedures

Routine, Periodic, and Calibration Tasks

Theory of Operation

General Description of Wire Feeders

Overview of the LF72 and LF74 wire feeders and their capabilities.

Control Board and Operator Interfaces

Describes how input voltage is processed and controls interact with the board.

Drive Motor, Tach, and Gas Solenoid Functions

Explains the function of the drive motor, tach feedback, and gas solenoid.

Troubleshooting and Repair Guide

Using the Troubleshooting Guide

Explains the three-step procedure for diagnosing and locating malfunctions.

PC Board Troubleshooting and Replacement

Guides for troubleshooting and replacing PC boards, including static precautions.

Common Function Problems and Solutions

Lists common problems, possible causes, and recommended solutions.

Component Testing Procedures

Detailed tests for motor, tach, solenoid, diode bridge, and potentiometer.

PC Board Removal and Replacement

Step-by-step guide for removing and installing the control PC board.

Wire Drive Motor and Gear Box Procedures

Procedures for removing and replacing the drive motor or gear box.

Post-Repair Testing and Verification