Lincoln Electric LF-72/74 service manual Set Up, Operation Verification

Page 105

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F-21	TROUBLESHOOTING AND REPAIR	F-21

	RETEST AFTER REPAIR

Retest a machine:

•If it is rejected under test for any reason that requires you to remove any part which could affect the machine’s electrical characteristics.

OR

• If you repair or replace any electrical components.

SET UP

1.Connect a supply of filtered compressed air at 80 psi to the gas inlet.

2.Supply 42VAC to the machine.

3.Connect the gun to the connector block.

OPERATION VERIFICATION

1.Close the idle arms and the pressure arms.

2.Activate the cold feed switch.

3.Verify the drive rolls are spinning in the forward direction.

4.Adjust the wire speed knob from min to max and verify the speed is changing.

5.Release the cold feed switch and verify that the drive rolls stop abruptly.

6.Activate the gas purge switch and verify that there is gas flow.

7.Release the gas purge switch and verify the gas flow stops.

8.Place the 2-step/trigger interlock switch in the trigger interlock position.

9.Activate the gun trigger and verify the drive rolls spin.

10.Release the gun trigger and verify the drive rolls continue to spin.

11.Activate and release the gun trigger and verify the drive rolls stop abruptly.

12.Place the 2-step/trigger interlock switch in the 2-step position.

LF-72/74

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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 Swivel Mount Bench MountBoom Mount SuspendedWeld 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 Welding GUN/WIRE Feeder Trigger Connector Wire Drive SystemsRemote Sense Lead Specifications High Frequency ProtectionMagnum 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 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 OperationCommon Welding Abbreviations Product DescriptionRecommended 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-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-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-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-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