Function Problems | Lincoln Electric LF-72/74 specs

Return to Section TOC

Return to Section TOC

Return to Section TOC

Return to Section TOC

Return to Master TOC

Return to Master TOC

Return to Master TOC

Return to Master TOC

F-4

TROUBLESHOOTING & REPAIR

F-4

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

The wire drive does not feed wire	1. Power source not on	1.	Verify the power source is on
and the drive rolls do not spin	2. Possible tripped breaker		Verify power is being applied to
	2. Possible tripped breaker		Verify power is being applied to
	3. Faulty gun trigger		the wire feeder
	3. Faulty gun trigger
	4. Possible faulty control cable	2.	Verify the circuit breaker of the
	4. Possible faulty control cable		wire feeder or the power source
			wire feeder or the power source
			has not tripped
		3.	Check to see if the gun trigger is
			working properly
		4.	Check for cable continuity, and
			for broken or bent pins.
The wire feeds erratically, or the	1. Wrong drive rolls installed.	1.	Verify the correct drive rolls and
motor LED lights.			inner wire guides are installed in
	2. Possible problem with gun		the wire drive
	3. Pressure arm or brake tension to	2.	Check for sharp bends in gun
	tight.		liner
	4. Examine the contact tip for wear	Check gun liner. The welding elec-
	or proper size	trode should slide easily through
		the gun. Verify proper gun liner is
		installed
		3.	Adjust brake tension. Adjust
			pressure arm see FIGURE A.6
		4.	Replace if necessary
		5.	If using wire conduit, verify that
			the wire slides easily through the
			conduit.
		6.	Perform the WIRE DRIVE
			MOTOR TEST. Perform TACH
			FEEDBACK TEST .

The wire continues to feed when	1. Trigger interlock switch in wrong	1.	Check if the 2 step/ trigger inter-
the gun trigger is released.	position.		lock switch is in the TRIGGER
			INTERLOCK position.
	2. Gun trigger shorted or stuck
		2.	Verify operation of the gun trig-
			ger. Check for shorted trigger
			leads.

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 SINGLE/DUAL

Image 88

Lincoln Electric LF-72/74 service manual Function Problems

Contents

LF-72/74 Safety Electric Shock can kill Welding Sparks can cause fire or explosion Iii Précautions DE Sûreté Sûreté Pour Soudage a L’Arc Master Table of Contents for ALL Sections Installation Section Table of ContentsSection A-1 Installation Amp Rating Duty Cycle Location Safety PrecautionMounting Bench Mount Swivel MountBoom Mount Suspended Weld Cable Sizes Coaxial Weld Cables Weld Cable Connection Analog Control Cable INSTALLATIONA-7Control Cable Connections Analog Miller Control Cable Adapter K2335-1 Miller Power Source Lincoln Wire FeederPin Function Wire Drive Systems Welding GUN/WIRE Feeder Trigger ConnectorRemote Sense Lead Specifications High Frequency Protection Welding GUNS, Torches and ACCES- Sories Magnum GUN and Cable Assemblies Wire 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 Weld Wire Routing Figure A.9 Shielding GAS Connection Installing Electrode To install Lincoln conduit See Figure A.10bConduit Kits For Codes 11209, 11210, 11211 and above Aluminum Wire Preparations Figure A.12b INSTALLATIONA-18 Base Model Bench Model Standard Duty Bench Model Heavy Duty Typical System Configurations Cable LF-72/74 Operation Section Section B-1 Operation GAS Input Work Connection Product Description Common Welding AbbreviationsRecommended Processes Front Panel Controls and Connections Figure B.1 Case Front Controls Description Burnback and Postflow Timer KIT Cold FEED/GAS Purge SwitchStep Trigger Interlock Switch Remote Voltage Control KIT Wire Feed Speed Knob Trigger Connector 5-PIN AmphenolGUN Receiver Bushing K1500-2 Trigger Interlock Accessories Section Section C-1 Accessories Optional Kits LF-72s Accessories Key LF-72/74 Maintenance Section Section D-1 Maintenance MaintenanceCalibration Specification Routine Maintenance Figure D.1 Figure D.3 Major Component Location Section AA-1 Section AA AA-2 WFS Range Wire SizesModel AA-3 Figure AA.1 AA-4 AA-5 AA-6 Coaxial Weld Cable AA-7 INSTALLATIONAA-7K1797-xx AA-8 Drive Roll Kits Steel or Cored Wires AA-9 AA-10 Figure AA.3 AA-11 Changing the Gun Receiver BushingLation or changing drive rolls and/or Guides Assembly of Drive Rolls and Wire Guides AA-12 AA-13 Set the pressure arm as follows See Figure AA.8 AA-14 AA-15 Loading 16 to 44 lb .3 20kg Spools See figure AA.8 AA-16 Figure AA.11 AA-17 Figure AA.12a AA-18 Figure AA.12b AA-19 AA-20INSTALLATIONAA-20 Common Equipment SET-UPS Figure AA.15 High Volume Production AA-21 Figure AA.16 Portable Welding AA-22 Section BB-1 Section BB BB-2 Fcaw Innershield or Outershield Required Equipment BB-3 BB-4 Figure BB.1 Case Front Controls Description K2426-1 and K2426-2 models BB-5K2426-3 model Switch BB-6 Section CC-1 CC-2 CC-3 CC-4 CC-5 CC-6 Section DD-1 Section DD To verify the wire feed speed Nal wiringWhen inching with gun trigger, electrode WFS knob setting Could remain energized Several seconds MAINTENANCEDD-3 DD-3 Figure DD.3 Major Component Location DD-4 Theory of Operation Section Section E-1 Theory of Operation Return to Section Control Board LF-72/74 Troubleshooting & Repair Section Section F-1 Troubleshooting & Repair HOW to USE Troubleshooting Guide PC Board Troubleshooting Procedures Function Problems Function Problems Troubleshooting & Repair Drive Motor and Tach Feedback Test Test Description Test Procedure Troubleshooting and Repair GAS Solenoid Test Test Procedure Figure F.3 Leads 552, 552B Diode Bridge Test 552B + 552A Wire Speed Potentiometer Test Wire Speed Potentiometer Test 14F-14 PC Board Removal and Replacement Control PC Board Removal and Replacement Procedure Removal Procedure Replacement Procedure Troubleshooting and Repair Wire Drive Motor and Gear BOX Removal and Replacement Procedure Procedure Replacement Procedures SET UP Operation Verification LF-72/74 Electrical Diagrams Section Section G-1 Electrical Diagrams LF-72/74 Timer 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