Lincoln Electric LF-72/74 service manual Troubleshooting & Repair

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F-6

TROUBLESHOOTING & REPAIR

F-6

LF-72/74

Observe Safety Guidelines detailed in the beginning of this manual.


	PROBLEMS	POSSIBLE AREAS OF	RECOMMENDED
	(SYMPTOMS)	MISADJUSTMENT(S)	COURSE OF ACTION

	FUNCTION PROBLEMS (Continued)
	The motor (L12081) failed when a	When testing the wire drives for	This can be done by loading a
	load (6 N m) was applied to the	feeding problems (“inconsistent	spool of wire, setting the spindle
	wire drive.	feeding”, “grinding noises from the	brake to maximum and hen feed-
		gearbox”, “jumping drive rolls”) the	ing wire.
		wire drive should be tested under
		load.

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con- tact the Lincoln Electric Service Department at 1-888-935-3877 for electrical troubleshooting assistance before you proceed.

LF-72/74

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Contents LF-72/74 Safety Electric Shock can kill Welding Sparks can cause fire or explosion IiiPrécautions DE Sûreté Sûreté Pour Soudage a L’ArcMaster Table of Contents for ALL Sections Table of Contents Installation SectionSection A-1 Installation Amp Rating Duty CycleSafety Precaution LocationMounting Boom Mount Bench MountSwivel Mount SuspendedWeld Cable Sizes Coaxial Weld Cables Weld Cable ConnectionINSTALLATIONA-7 Analog Control CableControl Cable Connections Miller Power Source Lincoln Wire Feeder Analog Miller Control Cable Adapter K2335-1Pin Function Remote Sense Lead Specifications Wire Drive SystemsWelding GUN/WIRE Feeder Trigger Connector High Frequency ProtectionWelding GUNS, Torches and ACCES- Sories Magnum GUN and Cable AssembliesProcedure 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 Weld Wire Routing Figure A.9Shielding GAS Connection Conduit Kits Installing ElectrodeTo install Lincoln conduit See Figure A.10b For Codes 11209, 11210, 11211 and aboveAluminum Wire Preparations Figure A.12bINSTALLATIONA-18 Base Model Bench Model Standard Duty Bench Model Heavy DutyTypical System Configurations CableLF-72/74 Operation Section Section B-1Operation GAS Input Work ConnectionCommon Welding Abbreviations Product DescriptionRecommended Processes Front Panel Controls and Connections Figure B.1 Case Front Controls DescriptionStep Trigger Interlock Switch Burnback and Postflow Timer KITCold FEED/GAS Purge Switch Remote Voltage Control KITGUN Receiver Bushing K1500-2 Wire Feed Speed KnobTrigger Connector 5-PIN Amphenol Trigger InterlockAccessories Section Section C-1Accessories Optional KitsLF-72s Accessories Key LF-72/74 Maintenance Section Section D-1Calibration Specification MaintenanceMaintenance Routine MaintenanceFigure D.1 Figure D.3 Major Component Location Section AA-1 Section AAWFS Range Wire Sizes AA-2Model AA-3 Figure AA.1AA-4 AA-5 AA-6 Coaxial Weld CableINSTALLATIONAA-7 AA-7K1797-xx AA-8 Drive Roll Kits Steel or Cored Wires AA-9AA-10 Figure AA.3Lation or changing drive rolls and/or AA-11Changing the Gun Receiver Bushing GuidesAssembly of Drive Rolls and Wire Guides AA-12AA-13 Set the pressure arm as follows See Figure AA.8AA-14 AA-15 Loading 16 to 44 lb .3 20kg Spools See figure AA.8AA-16 Figure AA.11AA-17 Figure AA.12aAA-18 Figure AA.12bAA-19 AA-20INSTALLATIONAA-20 Common Equipment SET-UPSFigure AA.15 High Volume Production AA-21Figure AA.16 Portable Welding AA-22Section BB-1 Section BBBB-2 Fcaw Innershield or OutershieldRequired Equipment BB-3BB-4 Figure BB.1 Case Front Controls DescriptionBB-5 K2426-1 and K2426-2 modelsK2426-3 model Switch BB-6Section CC-1 CC-2 CC-3 CC-4 CC-5 CC-6 Section DD-1 Section DDWhen inching with gun trigger, electrode To verify the wire feed speedNal wiring WFS knob setting Could remain energized Several secondsMAINTENANCEDD-3 DD-3Figure DD.3 Major Component Location DD-4Theory of Operation Section Section E-1Theory of Operation Return to SectionControl Board LF-72/74 Troubleshooting & Repair Section Section F-1Troubleshooting & Repair HOW to USE Troubleshooting Guide PC Board Troubleshooting Procedures Function Problems Function Problems Troubleshooting & Repair Drive Motor and Tach Feedback Test Test DescriptionTest Procedure Troubleshooting and Repair GAS Solenoid TestTest Procedure Figure F.3 Leads 552, 552BDiode Bridge Test 552B + 552A Wire Speed Potentiometer Test Wire Speed Potentiometer Test 14F-14PC Board Removal and Replacement Control PC Board Removal and Replacement Procedure Removal Procedure Replacement ProcedureTroubleshooting and Repair Wire Drive Motor and Gear BOX Removal and Replacement ProcedureProcedure Replacement Procedures SET UP Operation VerificationLF-72/74 Electrical Diagrams Section Section G-1Electrical Diagrams LF-72/74Timer 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