Lincoln Electric LF-72/74 service manual Electric Shock can kill

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SAFETY

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ELECTRIC SHOCK can kill.

3.a. The electrode and work (or ground) circuits are electrically “hot” when the welder is on. Do not touch these “hot” parts with your bare skin or wet clothing. Wear dry, hole-free gloves to insulate hands.

3.b. Insulate yourself from work and ground using dry insulation. Make certain the insulation is large enough to cover your full area of physical contact with work and ground.

In addition to the normal safety precautions, if welding must be performed under electrically hazardous conditions (in damp locations or while wearing wet clothing; on metal structures such as floors, gratings or scaffolds; when in cramped positions such as sitting, kneeling or lying, if there is a high risk of unavoidable or accidental contact with the workpiece or ground) use the following equipment:

Semiautomatic DC Constant Voltage (Wire) Welder.

DC Manual (Stick) Welder.

AC Welder with Reduced Voltage Control.

3.c. In semiautomatic or automatic wire welding, the electrode, electrode reel, welding head, nozzle or semiautomatic welding gun are also electrically “hot”.

3.d. Always be sure the work cable makes a good electrical connection with the metal being welded. The connection should be as close as possible to the area being welded.

3.e. Ground the work or metal to be welded to a good electrical (earth) ground.

3.f. Maintain the electrode holder, work clamp, welding cable and welding machine in good, safe operating condition. Replace damaged insulation.

3.g. Never dip the electrode in water for cooling.

3.h. Never simultaneously touch electrically “hot” parts of electrode holders connected to two welders because voltage between the two can be the total of the open circuit voltage of both welders.

3.i. When working above floor level, use a safety belt to protect yourself from a fall should you get a shock.

3.j. Also see Items 6.c. and 8.

ARC RAYS can burn.

4.a. Use a shield with the proper filter and cover plates to protect your eyes from sparks and the rays of the arc when welding or observing open arc welding. Headshield and filter lens should conform to ANSI Z87. I standards.

4.b. Use suitable clothing made from durable flame-resistant material to protect your skin and that of your helpers from the arc rays.

4.c. Protect other nearby personnel with suitable, non-flammable screening and/or warn them not to watch the arc nor expose themselves to the arc rays or to hot spatter or metal.

FUMES AND GASES can be dangerous.

5.a. Welding may produce fumes and gases hazardous to health. Avoid breathing these fumes and gases.When welding, keep your head out of the fume. Use enough ventilation and/or exhaust at the arc to keep

fumes and gases away from the breathing zone. When welding with electrodes which require special ventilation such as stainless or hard facing (see instructions on container or MSDS) or on lead or cadmium plated steel and other metals or coatings which produce highly toxic fumes, keep exposure as low as possible and below Threshold Limit Values (TLV) using local exhaust or mechanical ventilation. In confined spaces or in some circumstances, outdoors, a respirator may be required. Additional precautions are also required when welding on galvanized steel.

5.b. The operation of welding fume control equipment is affected by various factors including proper use and positioning of the equipment, maintenance of the equipment and the specific welding procedure and application involved. Worker expo- sure level should be checked upon installation and periodi- cally thereafter to be certain it is within applicable OSHA PEL and ACGIH TLV limits.

5.c. Do not weld in locations near chlorinated hydrocarbon vapors coming from degreasing, cleaning or spraying operations. The heat and rays of the arc can react with solvent vapors to form phosgene, a highly toxic gas, and other irritating prod- ucts.

5.d. Shielding gases used for arc welding can displace air and cause injury or death. Always use enough ventilation, especially in confined areas, to insure breathing air is safe.

5.e. Read and understand the manufacturer’s instructions for this equipment and the consumables to be used, including the material safety data sheet (MSDS) and follow your employer’s safety practices. MSDS forms are available from your welding distributor or from the manufacturer.

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5.f. Also see item 1.b.

AUG 06

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Contents LF-72/74 Safety Electric Shock can kill Iii Welding Sparks can cause fire or explosionSûreté Pour Soudage a L’Arc Précautions DE SûretéMaster Table of Contents for ALL Sections Table of Contents Installation SectionSection A-1 Amp Rating Duty Cycle InstallationSafety Precaution LocationMounting Suspended Bench MountSwivel Mount Boom MountWeld Cable Sizes Weld Cable Connection Coaxial Weld CablesINSTALLATIONA-7 Analog Control CableControl Cable Connections Miller Power Source Lincoln Wire Feeder Analog Miller Control Cable Adapter K2335-1Pin Function High Frequency Protection Wire Drive SystemsWelding GUN/WIRE Feeder Trigger Connector Remote Sense Lead SpecificationsMagnum GUN and Cable Assemblies Welding GUNS, Torches and ACCES- SoriesProcedure for Changing Drive and Idle Roll Sets Wire Drive ConfigurationRolls.FIGURE A.4 Pressure ARM Adjustment Gun Receiver For use With BushingSet the pressure arm as follows See Figure A.6 Wire Reel Loading Figure A.9 Weld Wire RoutingShielding GAS Connection For Codes 11209, 11210, 11211 and above Installing ElectrodeTo install Lincoln conduit See Figure A.10b Conduit KitsFigure A.12b Aluminum Wire PreparationsBase Model Bench Model Standard Duty Bench Model Heavy Duty INSTALLATIONA-18Cable Typical System ConfigurationsLF-72/74 Section B-1 Operation SectionGAS Input Work Connection OperationCommon Welding Abbreviations Product DescriptionRecommended Processes Figure B.1 Case Front Controls Description Front Panel Controls and ConnectionsRemote Voltage Control KIT Burnback and Postflow Timer KITCold FEED/GAS Purge Switch Step Trigger Interlock SwitchTrigger Interlock Wire Feed Speed KnobTrigger Connector 5-PIN Amphenol GUN Receiver Bushing K1500-2Section C-1 Accessories SectionOptional Kits AccessoriesLF-72s Accessories Key LF-72/74 Section D-1 Maintenance SectionRoutine Maintenance MaintenanceMaintenance Calibration SpecificationFigure D.1 Figure D.3 Major Component Location Section AA Section AA-1WFS Range Wire Sizes AA-2Model Figure AA.1 AA-3AA-4 AA-5 Coaxial Weld Cable AA-6INSTALLATIONAA-7 AA-7K1797-xx AA-8 AA-9 Drive Roll Kits Steel or Cored WiresFigure AA.3 AA-10Guides AA-11Changing the Gun Receiver Bushing Lation or changing drive rolls and/orAA-12 Assembly of Drive Rolls and Wire GuidesSet the pressure arm as follows See Figure AA.8 AA-13AA-14 Loading 16 to 44 lb .3 20kg Spools See figure AA.8 AA-15Figure AA.11 AA-16Figure AA.12a AA-17Figure AA.12b AA-18AA-19 Common Equipment SET-UPS AA-20INSTALLATIONAA-20AA-21 Figure AA.15 High Volume ProductionAA-22 Figure AA.16 Portable WeldingSection BB Section BB-1Fcaw Innershield or Outershield BB-2BB-3 Required EquipmentFigure BB.1 Case Front Controls Description BB-4BB-5 K2426-1 and K2426-2 modelsK2426-3 model BB-6 SwitchSection CC-1 CC-2 CC-3 CC-4 CC-5 CC-6 Section DD Section DD-1WFS knob setting Could remain energized Several seconds To verify the wire feed speedNal wiring When inching with gun trigger, electrodeDD-3 MAINTENANCEDD-3DD-4 Figure DD.3 Major Component LocationSection E-1 Theory of Operation SectionReturn to Section Theory of OperationControl Board LF-72/74 Section F-1 Troubleshooting & Repair SectionHOW to USE Troubleshooting Guide Troubleshooting & RepairPC Board Troubleshooting Procedures Function Problems Function Problems Troubleshooting & Repair Test Description Drive Motor and Tach Feedback TestTest Procedure GAS Solenoid Test Troubleshooting and RepairFigure F.3 Leads 552, 552B Test ProcedureDiode Bridge Test 552B + 552A Wire Speed Potentiometer Test 14F-14 Wire Speed Potentiometer TestPC Board Removal and Replacement Removal Procedure Replacement Procedure Control PC Board Removal and Replacement ProcedureTroubleshooting and Repair Procedure Wire Drive Motor and Gear BOX Removal and ReplacementProcedure Replacement Procedures Operation Verification SET UPLF-72/74 Section G-1 Electrical Diagrams SectionLF-72/74 Electrical DiagramsTimer KIT Board Normal Speed Micro Internal panel Motor Connecter Summary High Torque Setting engages Schematic Common Analog Control PC Board G4559 Sheet Electrical Diagrams Electrical Diagrams PC Board Assembly Common Analog Control G4560-2E0