Wire Feed Speed Knob, Trigger Interlock | Lincoln Electric LF-72/74

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B-6	OPERATION	B-6

Trigger Interlock

Trigger Interlock operation provides for operator com- fort when making long welds. When the gun trigger is first pulled, the welding power source energizes the output and the wire feeder feeds wire for welding. The gun trigger is then released while the weld is made. To stop welding, the gun trigger is pulled again, and when it is released the welding power source output turns off and the wire feeder stops feeding wire.

CAUTION

•If the arc goes out while welding with trigger interlock operation, the elec- trode output from the welding power source remains energized and the wire feeder will continue to feed wire until the gun trigger is again pulled and then released.

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6. WIRE FEED SPEED KNOB

The large, calibrated wire feed speed knob makes for easy and accurate adjustment of the wire feed speed. The knob rotates 3/4 turn. Turn the knob clockwise to increase the wire feed speed, and counter clockwise to reduce the wire feed speed.

The wire feed speed range is 50 to 800 in/min (1.27 -

20.3m/min).

7.GUN RECEIVER BUSHING (K1500-2)

(K1500-2 bushing is standard on all LF-72's)

This Gun Receiver Bushing is used with Lincoln gun connectors, also with Magnum 200/300/400 guns and compatible with Tweco® #4).

8. TRIGGER CONNECTOR 5-PIN AMPHENOL

This is used for connecting the MIG gun trigger. See

Installation Section for detail.

LF-72/74

Image 32

Lincoln Electric LF-72/74 Wire Feed Speed Knob, GUN Receiver Bushing K1500-2, Trigger Connector 5-PIN Amphenol

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 Section A-1 Table of ContentsInstallation Section Installation Amp Rating Duty Cycle Mounting Safety PrecautionLocation Bench Mount Swivel MountBoom Mount Suspended Weld Cable Sizes Coaxial Weld Cables Weld Cable Connection Control Cable Connections INSTALLATIONA-7Analog Control Cable Pin Function Miller Power Source Lincoln Wire FeederAnalog Miller Control Cable Adapter K2335-1 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 Rolls.FIGURE A.4 Procedure for Changing Drive and Idle Roll SetsWire Drive Configuration Set the pressure arm as follows See Figure A.6 Pressure ARM AdjustmentGun Receiver For use With Bushing 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 Recommended Processes Common Welding AbbreviationsProduct Description 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 Model WFS Range Wire SizesAA-2 AA-3 Figure AA.1 AA-4 AA-5 AA-6 Coaxial Weld Cable K1797-xx INSTALLATIONAA-7AA-7 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 K2426-3 model BB-5K2426-1 and K2426-2 models 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