Lincoln Electric LF-72/74 service manual Troubleshooting & Repair Section, Section F-1

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Section F-1	TABLE OF CONTENTS	Section F-1
	- TROUBLESHOOTING & REPAIR SECTION -

Troubleshooting & Repair Section	Section F
How to Use Troubleshooting Guide	F-2
PC Board Troubleshooting Procedures and Replacement	F-3
Troubleshooting Guide	F-4
Test Procedures
Drive Motor and Tach Feedback Test	F-7/F-8
Gas Solenoid Test	F-9/F-10
Diode Bridge Test	F-11/F-12
Wire Speed Potentiometer Test	F-13/F-14
Replacement Procedures
PC Board Removal and Replacement	F-15/F-16
Wire Drive Motor and Gear Box Removal and Replacement	F-17/F-20
Retest After Repair	F-21

LF-72/74 SINGLE/DUAL

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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 Installation Section Table of ContentsSection A-1 Amp Rating Duty Cycle InstallationLocation Safety PrecautionMounting Swivel Mount Bench MountBoom Mount SuspendedWeld Cable Sizes Weld Cable Connection Coaxial Weld CablesAnalog Control Cable INSTALLATIONA-7Control Cable Connections Analog Miller Control Cable Adapter K2335-1 Miller Power Source Lincoln Wire FeederPin Function Welding GUN/WIRE Feeder Trigger Connector Wire Drive SystemsRemote Sense Lead Specifications High Frequency ProtectionMagnum GUN and Cable Assemblies Welding GUNS, Torches and ACCES- SoriesWire Drive Configuration Procedure for Changing Drive and Idle Roll SetsRolls.FIGURE A.4 Gun Receiver For use With Bushing Pressure ARM AdjustmentSet the pressure arm as follows See Figure A.6 Wire Reel Loading Figure A.9 Weld Wire RoutingShielding GAS Connection To install Lincoln conduit See Figure A.10b Installing ElectrodeConduit Kits For Codes 11209, 11210, 11211 and aboveFigure 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 OperationProduct Description Common Welding AbbreviationsRecommended Processes Figure B.1 Case Front Controls Description Front Panel Controls and ConnectionsCold FEED/GAS Purge Switch Burnback and Postflow Timer KITStep Trigger Interlock Switch Remote Voltage Control KITTrigger Connector 5-PIN Amphenol Wire Feed Speed KnobGUN Receiver Bushing K1500-2 Trigger InterlockSection C-1 Accessories SectionOptional Kits AccessoriesLF-72s Accessories Key LF-72/74 Section D-1 Maintenance SectionMaintenance MaintenanceCalibration Specification Routine MaintenanceFigure D.1 Figure D.3 Major Component Location Section AA Section AA-1AA-2 WFS Range Wire SizesModel Figure AA.1 AA-3AA-4 AA-5 Coaxial Weld Cable AA-6AA-7 INSTALLATIONAA-7K1797-xx AA-8 AA-9 Drive Roll Kits Steel or Cored WiresFigure AA.3 AA-10Changing the Gun Receiver Bushing AA-11Lation or changing drive rolls and/or GuidesAA-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-4K2426-1 and K2426-2 models BB-5K2426-3 model BB-6 SwitchSection CC-1 CC-2 CC-3 CC-4 CC-5 CC-6 Section DD Section DD-1Nal wiring To verify the wire feed speedWhen inching with gun trigger, electrode WFS knob setting Could remain energized Several secondsDD-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