Lincoln Electric LF-72/74 Service Manual
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Lincoln Electric LF-72/74 Service Manual

Lincoln electric welder user manual
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SVM171-A
RETURN TO MAIN MENU
January, 2007
LF- 72/74
For use with machines having Code Number : 11075 thru 11293
Safety Depends on You
Lincoln arc welding and cutting
equipment is designed and built
with safety in mind. However,
your overall safety can be
increased by proper installation
. . . and thoughtful operation on
your part. DO NOT INSTALL,
OPERATE OR REPAIR THIS
EQUIPMENT WITHOUT READ-
ING THIS MANUAL AND THE
SAFETY PRECAUTIONS CON-
TAINED THROUGHOUT. And,
most importantly, think before
you act and be careful.

SERVICE MANUAL

Copyright © 2007 Lincoln Global Inc.
• World's Leader in Welding and Cutting Products •
• Sales and Service through Subsidiaries and Distributors Worldwide •
Cleveland, Ohio 44117-1199 U.S.A. TEL: 1-888-935-3877 FAX: 216.486.1751 WEB SITE: www.lincolnelectric.com

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Summary of Contents for Lincoln Electric LF-72/74

  • Page 1: Service Manual

    SVM171-A RETURN TO MAIN MENU January, 2007 LF- 72/74 For use with machines having Code Number : 11075 thru 11293 Safety Depends on You Lincoln arc welding and cutting equipment is designed and built with safety in mind. However, your overall safety can be increased by proper installation .

  • Page 2: California Proposition 65 Warnings

    Miami, Florida 33135 or CSA Standard W117.2-1974. A Free copy of “Arc Welding Safety” booklet E205 is available from the Lincoln Electric Company, 22801 St. Clair Avenue, Cleveland, Ohio 44117-1199. BE SURE THAT ALL INSTALLATION, OPERATION, MAINTENANCE AND REPAIR PROCEDURES ARE PERFORMED ONLY BY QUALIFIED INDIVIDUALS.

  • Page 3: Electric Shock Can Kill

    ELECTRIC SHOCK can kill. 3.a. The electrode and work (or ground) circuits are electrically “hot” when the welder is on. Do not touch these “hot” parts with your bare skin or wet clothing. Wear dry, hole-free gloves to insulate hands.
  • Page 4 WELDING SPARKS can cause fire or explosion. 6.a. Remove fire hazards from the welding area. If this is not possible, cover them to prevent the welding sparks from starting a fire. Remember that welding sparks and hot materials from welding can easily go through small cracks and openings to adjacent areas.
  • Page 5 PRÉCAUTIONS DE SÛRETÉ Pour votre propre protection lire et observer toutes les instructions et les précautions de sûreté specifiques qui parraissent dans ce manuel aussi bien que les précautions de sûreté générales suiv- antes: Sûreté Pour Soudage A L’Arc 1. Protegez-vous contre la secousse électrique: a.
  • Page 6 Parts Manual ..........P501 Series (LF-72) P518 Series (LF-74) LF-72/74...

  • Page 7: Table Of Contents

    Pressure Arm Adjustment ...A-12 Wire Reel Loading...A-13 Weld Wire Routing ...A-14 Sheilding Gas Connections...A-15 Installing Electrode Conduit Kits ...A-16 Aluminum Wire Preperations...A-17 Base Model, Bench Model Standard Duty and Bench Model Heavy Duty...A-18 Typical System Configurations...A-19 TABLE OF CONTENTS LF-72/74 SINGLE/DUAL Section A-1...

  • Page 8: Installation

    Depth Weight 15.3“ 13.0“ 27.7“ 67.5 Lbs ( 389 mm) (330 mm) (704 mm) (30.6 Kg.) LF-72/74 Cored .035 - 5/64 in (0.9 - 2.0 mm) TEMPERATURE RATING Operating Storage 14°F to 104°F -40°F to 85°F (-10°C to 40°C) (-40°C to 85°C)

  • Page 9: Safety Precautions

    Place the LF-72 in a clean and dry location. Do not stack the LF-72. INSTALLATION MOUNTING For location and size, LF-72 Bench Model Rear Mounting Holes (See Figure A.1) and for Bottom Mounting Holes (See Figure A.2). FIGURE A.2 LF-72/74 FIGURE A.1...

  • Page 10: Bench Mount

    Only suspend the wire feeder by the lift bail of the portability kit. WARNING Alternative methods for hanging the wire feeder must not be used unless insulation is provided between the wire feeder enclosure and the hanging device. ------------------------------------------------------------------------ LF-72/74...

  • Page 11: Weld Cable Sizes

    WELD CABLE SIZES Table A.1 has the copper cable sizes recommended for different currents and duty cycles. Lengths stipulated are the distance from the welder to work and back to the welder again. greater lengths primarily for the purpose of minimizing voltage in the welding circuit.

  • Page 12: Coaxial Weld Cables

    Be sure the connection to the work makes tight metal to metal electrical contact. Poor work lead connections can result in poor welding performance. Work Electrode Work Coaxial Weld Cable LF-72/74 Wire Feeder Electrode Work...

  • Page 13: Analog Control Cable Connections

    Welding Output Control (trigger from feeder) Welding Output Control (trigger from feeder) Remote Voltage Control Remote Voltage Control Remote Voltage Control Reserved 42 VAC Reserve for Future Use. 42 VAC Reserve for Future Use. Unused ------- Electrode voltage from feeder LF-72/74...
  • Page 14 Referenced to pin D. 24 VAC common. Arc Voltage feedback to feeder. Scaled 0-10V. 1 V = 10 Arc volts. Referenced to pin D. Miller is a registered trademark not owned or licensed by The Lincoln Electric Company. NOTES MILLER CONTROL WIRE FEEDER...

  • Page 15: Welding Gun/Wire Feeder Trigger Connector

    Includes: 2 polished U groove drive rolls, outer wire guide and an inner wire guide. KP1695-035A KP1695-040A KP1695-3/64A KP1695-1/16A INNER WIRE GUIDE LF-72/74 .023-.030 (0.6-0.8mm) .035 (0.9mm) .045 (1.2mm) .052 (1.4mm) 1/16 (1.6mm) .035, .O45 (0.9, 1.2mm) .040 (1.0mm) .030-.035" (0.8-0.9mm) .040-.045"...

  • Page 16: Welding Guns, Torches And Accesories

    4. Connect the gun trigger connector to the trigger receptacle. Make sure that the key ways are aligned and insert. LF-72 BASE MODEL GUN RECEIVER BUSHING (INTERCHANGABLE) WIRE DRIVE UNIT GUN TUBE GUN NOZZLE GUN TRIGGER CONNECTOR CABLE CONNECTOR END K466-10 LF-72/74 A-10...

  • Page 17: Procedure For Changing Drive And Idle Roll Sets

    Because of the preci- sion fit, light tapping may be required to remove the gun bushing. FIGURE A.5 THUMB SCREW GUN RECEIVER BUSHING CONNECTOR BLOCK SOCKET HEAD CAP SCREW LF-72/74 A-11 OUTER WIRE GUIDE LOOSEN TIGHTEN...

  • Page 18: Pressure Arm Adjustment

    Set the pressure arm as follows (See Figure A.6): Aluminum wires Cored wires Steel, Stainless wires FIGURE A.6 CORED WIRES OUTERSHIELD METALSHIELD INNERS HIELD LF-72/74 A-12 between 1 and 3 between 3 and 4 between 4 and 6 SOLID WIRES ALUMINUM STEEL STAINLE SS...

  • Page 19: Wire Reel Loading

    Removing a Readi-Reel 1. To remove a Readi-Reel from the an adapter, depress the retaining spring with a thumb while pulling the Readi-Reel cage from the adapter with both hands. Do not remove the adapter from the spindle. LF-72/74 A-13 Retaining Collar...

  • Page 20: Weld Wire Routing

    If more than one wire feed unit shares the same boom and are not sharing the some power source output stud, their wire and reels must be insulated from each other as well as insulated from their mounting structure. INSTALLATION FIGURE A.9 LF-72/74 A-14...

  • Page 21: Shielding Gas Connection

    • Keep cylinder upright and chained to support. • Keep cylinder away from areas where it may be damaged. • Never lift welder with cylinder attached. • Never allow welding electrode to touch cylinder. • Keep cylinder away from welding or other live electrical circuits.

  • Page 22: Installing Electrode Conduit Kits

    4. Tighten the set screw to secure the conduit connec- tor in the wire drive. 5. Insert conduit through the sheet metal of the LF-72 and into the conduit connector. Secure with the thumb screw. FIGURE A.11 LF-72/74 A-16 "O" RING...

  • Page 23: Aluminum Wire Preperations

    Remove the balls and the steel washer. FIGURE A.13 4. Place the ball bushing housing into the wire feeder case and secure with the snap ring or “O” ring depending on which code your machine uses. LF-72/74 A-17 "O" RING...
  • Page 24 INSTALLATION A-18 A-18 BASE MODEL BENCH MODEL STANDARD DUTY BENCH MODEL HEAVY DUTY LF-72/74...

  • Page 25: Typical System Configurations

    Base Model INSTALLATION TABLE 1 Wire Reel Stand Standard duty, up to 15', Magnum 400, 44 lb. (20 kg)spools. Heavy Duty, up to 60 lb. (27.2 kg) coils. LF-72/74 A-19 Drive Roll Kit CONTROL CABLE .035-.045 combo (0.9-1.2 mm) 10’ (3m)
  • Page 26 NOTES A-20 A-20 LF-72/74...

  • Page 27: Operation Section

    3. Thermal LED, Motor Overload ...B-5 4. Cold Feed/Gas Purge Switch ...B-5 5. 2 Step - Trigger Interlock Switch...B-5/B-6 6. Wire Feed Speed Knob ...B-6 7. Gun Receiver Bushing ...B-6 8. Trigger Connector 5-Pin Amphenol ...B-6 TABLE OF CONTENTS LF-72/74 SINGLE/DUAL Section B-1...

  • Page 28: Operation

    LF-72 wire feeder is and must be the sole respon- sibility of the builder/user. Many variables beyond the control of The Lincoln Electric Company affect the results obtained in using the LF-72 wire feeder. These variables include, but are not limited to, weld-...

  • Page 29: Common Welding Abbreviations

    • The K1733-1 wire straightener may not be used with the LF-72 • Gun bushings are required for welding guns that do not have a Magnum (Tweco #2-#4 compatible) back end. • The LF-72 does not attach to K303 wire reel stands. LF-72/74 Maximum...

  • Page 30: Front Panel Controls And Connections

    Press the switch down for gas flow with weld output off. 2 step - Trigger Interlock switch. Wire Feed Speed Knob. Gun Receiver Bushing. Trigger Connector 5-pin amphenol for connecting the MIG gun trigger. See Installation Section for detail. OPERATION DESCRIPTION LF-72/74...

  • Page 31: Remote Voltage Control Kit (Optional

    Perform regular maintenance and cleaning on the gun liner, conduit and gun. Always use quality electrode, such as L-50 or L-56 from Lincoln Electric. 4. COLD FEED/GAS PURGE SWITCH Cold Feed and Gas Purge are combined into a single spring centered toggle switch.

  • Page 32: Wire Feed Speed Knob

    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. OPERATION LF-72/74...
  • Page 33 TABLE OF CONTENTS Section C-1 Section C-1 - ACCESSORIES SECTION - Accessories ...Section C General Options / Accessories ...C-2/C-5 LF-72/74 SINGLE/DUAL...

  • Page 34: Optional Kits

    Includes: Twist-Mate to Twist- Mate, 2/0 Cable for 50' (15.2m) cables. Includes: Lug to Lug, 3/0 Cable of length "xx" for lengths up to 60' (18.3m). Lug to Lug, 4/0 Cable of length "xx" for lengths greater than 60' (18.3m). LF-72/74...
  • Page 35 Includes: Gun receiver bush- ing with hose nipple, set screw and hex key wrench. Includes: Gun receiver bush- ing with hose nipple, 4 guide tubes, set screw and hex key wrench. LF-72/74...
  • Page 36 Includes: Spindle Adapter made from 2 coil retainers. (Electrode not included.) Includes: Spindle Adapter. Includes: Readi-Reel spool adapter. (Spool of electrode not included.) Includes: Readi-Reel spool adapter. (Spool of electrode not included.) Includes: 50-60 lb. (22.7 - 27.2 kg) coil adapter. LF-72/74...
  • Page 37 (3.0m) Hose. Includes: Heavy Duty Wire Reel Stand. Includes: Undercarriage with 8" (203mm) rear wheels, 4" (102mm)casters. Includes: Swivel Platform and Tray. Includes: 2 Swivel Casters, 2 Fixed Casters, brackets and mounting hardware. Includes: Insulated Lift Bail and mounting hardware. LF-72/74...
  • Page 38 NOTES LF-72/74...
  • Page 39 TABLE OF CONTENTS Section D-1 Section D-1 - MAINTENANCE SECTION - Maintenance ...Section D Safety Precautions ...D-2 Routine Maintenance...D-2 Periodic Maintenance...D-2 Calibration Specification ...D-2/D-3 Major Component Locations...D-4 LF-72/74 SINGLE/DUAL...

  • Page 40: Calibration Specification

    1. Turn off power to the LF-72. 2. Disconnect the electrode lead from the feedplate and from the welding power source. 3. Remove the 5 screws securing the wraparound. (The door is not shown for clarity. “See Figure D.1”) LF-72/74 WARNING...
  • Page 41 17. Release the gun trigger. MAINTENANCE FIGURE D.1 (For Codes above 11290 use 18) 18. Replace P2 from the harness into connector J2. 19. Turn off power. 20. Secure the wraparound to the LF-72 with 5 screws. FIGURE D.2 LF-72/74 SINGLE/DUAL J2 CONNECTOR...
  • Page 42 MAINTENANCE 1. Center Assembly 2. Wire Drive Assembly 3. Wire Reel Stand LF-72 4. Wire Reel Stand LF-74 FIGURE D.3 - MAJOR COMPONENT LOCATION LF-72/74...
  • Page 43 Wire Reel Loading ...AA-15 Weld Wire Routing...AA-16 Installing Electrode Conduit Kits...AA-17 Aluminum Wire Preparations ...AA-18 Base Model, Bench Model and Extra Torque Bench Model ...AA-19 Common Equipment Set-Ups ...AA-20 High Volume Production ...AA-21 Portable Welding...AA-22 TABLE OF CONTENTS LF-72/74 Section AA-1...

  • Page 44: Installation

    ( 389 mm) (330 mm) (704 mm) (32.0 Kg.) Wire Reel Stand ----------- Heavy Duty, up to 60lb. (27.k kg) Coils LF-72/74 AA-2 FCAW WFS Range Wire Sizes .030 - 5/64” 100 – 800 ipm (0.8 - 2.0mm) (2.5-20.3 m/min.) .030 –...

  • Page 45: Safety Precautions

    (4 PLACES) (4 PLACES) FIGURE AA.2 1/4-20 1/4-20 THREADS THREADS (4 PLACES) (4 PLACES) 5/16-18 THREADS 5/16-18 THREADS (4 PLACES) (4 PLACES) LF-72/74 AA-3 MOUNTING FEET MOUNTING FEET SECURED WITH SECURED WITH #10-24 SCREWS #10-24 SCREWS (4 PLACES) (4 PLACES)

  • Page 46: Bench Mount

    K2426-1 shown with K2328-1Standard Duty Wire Reel Stand and K2331-1 Lift Bail Alternative methods for hanging the wire feeder must not be used unless insulation is provided between the wire feeder enclosure and the hanging device. ------------------------------------------------------------------------ LF-72/74 AA-4 WARNING...

  • Page 47: Weld Cable Sizes

    WELD CABLE SIZES Table A.1 has the copper cable sizes recommended for different currents and duty cycles. Lengths stipulated are the distance from the welder to work and back to the welder again. greater lengths primarily for the purpose of minimizing voltage in the welding circuit.

  • Page 48: Coaxial Weld Cables

    Be sure the connection to the work makes tight metal to metal electrical contact. Poor work lead connections can result in poor welding performance. Work Electrode Work Coaxial Weld Cable LF-72/74 AA-6 Wire Feeder Electrode Work...
  • Page 49 Remote Voltage Control (“+” supply from feeder or remote) Remote Voltage Control (control signal from feeder or remote) Remote Voltage Control (“-” supply from feeder or remote) Reserved 42 VAC Reserved 42 VAC Reserved Reserved ------- Electrode voltage from feeder LF-72/74 AA-7...
  • Page 50 Referenced to pin D. 24 VAC common. Arc Voltage feedback to feeder. Scaled 0-10V. 1 V = 10 Arc volts. Referenced to pin D. Miller is a registered trademark not owned or licensed by The Lincoln Electric Company. INSTALLATION MILLER CONTROL 720 ipm...

  • Page 51: Welding Gun/Wire Feeder Trigger Connector

    KP1505-3/32 Drive Roll Kits, Aluminum Wire Includes: 4 polished U groove drive rolls, outer wire guide and inner wire guide. KP1507-035A KP1507-040A KP1507-3/64A KP1507-1/16A LF-72/74 AA-9 .030-.035" (0.8-0.9mm) .040-.045" (1.0-1.2mm) .052" (1.4mm) 1/16" (1.6mm) .068-.072" (1.8mm) 5/64" (2.0mm) 3/32" (2.4mm) .035"...

  • Page 52: Welding Guns, Torches And Accessories

    3. Fully insert the gun cable connector end into the gun receiver bushing and gently tighten the thumb screw as show in Figure AA.3 below. 4. Connect the gun trigger connector to the trigger receptacle. Make sure that the key ways are aligned and insert. LF-72/74 AA-10...

  • Page 53: Wire Drive Configuration

    Magnum 550 guns and compatible with Tweco® #5) K1500-4 K466-3 Lincoln gun connectors; compatible with Miller® guns.) K1500-5 (Compatible with Oxo® guns.) K489-7 ( Lincoln Fast-Mate guns.) FIGURE AA.5 LOOSEN SCREW THUMB SCREW SOCKET HEAD CAP SCREW LF-72/74 AA-11 For use With TIGHTEN SCREW...

  • Page 54: Assembly Of Drive Rolls And Wire Guides

    7. Assemble the outer wire guide. 8. Adjust the pressure arms to the recommended set- ting. FIGURE AA.7 FIGURE AA.7a TRIANGULAR RING IN UNLOCKED POSITION LF-72/74 AA-12 DRIVE HUBS PRESSURE ARMS IN OPEN POSITION INNER WIRE GUIDE DRIVE ROLLS SLIDE DRIVE ROLL...

  • Page 55: Pressure Arm Adjustment

    Set the pressure arm as follows (See Figure AA.8): Aluminum wires Cored wires Steel, Stainless wires CORED WIRES OUTERSHIELD METALSHIELD INNERS HIELD INSTALLATION WARNING between 1 and 3 between 3 and 4 between 4 and 6 FIGURE AA.8 SOLID WIRES ALUMINUM STEEL STAINLE SS LF-72/74 AA-13...

  • Page 56: Shielding Gas Connection

    • Keep cylinder upright and chained to support. • Keep cylinder away from areas where it may be damaged. • Never lift welder with cylinder attached. • Never allow welding electrode to touch cylinder. • Keep cylinder away from welding or other live electrical circuits.

  • Page 57: Wire Reel Loading

    Removing a Readi-Reel 1. To remove a Readi-Reel from the an adapter, depress the retaining spring with a thumb while pulling the Readi-Reel cage from the adapter with both hands. Do not remove the adapter from the spindle. LF-72/74 AA-15 Retaining Collar...

  • Page 58: Weld Wire Routing

    If more than one wire feed unit shares the same boom and are not sharing the some power source output stud, their wire and reels must be insulated from each other as well as insulated from their mounting structure. INSTALLATION FIGURE AA.11 LF-72/74 AA-16...

  • Page 59: Installing Electrode Conduit Kits

    6. Mount the wire drive panel to the sheet metal hous- ing with the six screws. 7. Insert conduit through the sheet metal of the LF-74 and into the conduit connector. Secure with the thumb screw. INCOMING BUSHING BALL BUSHING ASSEMBLY O-RING SET SCREW LF-72/74 AA-17 CONDUIT CONNECTOR THUMB SCREW...

  • Page 60: Aluminum Wire Preparations

    Caution: as the screws are being loosened, the balls may fall free from the assembly. Remove the balls and the steel washer. INSTALLATION FIGURE AA.13 4. Place the ball bushing housing into the wire feeder case and secure with the “O” ring. LF-72/74 AA-18...
  • Page 61 INSTALLATION AA-19 AA-19 BASE MODEL (K2426-1) BENCH MODEL WITH HEAVY DUTY WIRE STAND (K2426-2) EXTRA TORQUE BENCH MODEL WITH HEAVY DUTY WIRE STAND (K2426-3) LF-72/74...

  • Page 62: Common Equipment Set-Ups

    LF-74 Bench Model with Heavy Duty Wire Reel Stand .035, .045 (0.9mm, 1.2mm) Drive Roll Kit 10' (3m) Control Cable Magnum Gun Deluxe Regulator for Mixed Shielding Gases Shielding Gas Hose Swivel Kit Ground Clamp Weld Power Cables, Twist-Mate to Lug (2 included) CV-305 LF-72/74 AA-20...
  • Page 63 Welding Arm Deluxe Gas Regulator for Mixed Gases Shielding Gas Hose Accu-Trak Drum Payoff Kit (Round) Accu-Pak Box Payoff Kit (Square) CV-400 Ground Clamp Weld Power Cable, Lug to Lug Incoming Bushing, .035-1/16 (0.9 - 1.6 mm) Conduit LF-72/74 AA-21...
  • Page 64 Control Cable Extension. Add cables to extend up to 110' (30m) Insulated Lift Bail Kit 4 Wheeled Undercarriage Plastic Wire Cover for 50-60lb. Wire Packages Deluxe Gas Regulator Shielding Gas Hose Ground Clamp Weld Power Cables, Twist Mate to Lug Welding Power Source LF-72/74 AA-22...
  • Page 65 Section BB-1 - OPERATION SECTION - Operation...Section BB Safety Precautions ...BB-2 Graphic Symbols ...BB-2 Common Welding Abbreviations ...BB-2 Product Description ...BB-3 Recommended Processes and Required Equipment ...BB-3 Front Panel Controls and Connections ...BB-4 1. Wire Feed Speed Knob ...BB-5 2. Remote Voltage Control Kit (Optional) ...BB-5 3.

  • Page 66: Operation

    CAUTION DANGEROUS VOLTAGE SHOCK HAZARD WELDING FUMES EXPLOSION GAS INPUT WORK CONNECTION COMMON WELDING ABBREVIATIONS • Wire Feed Speed • Constant Voltage GMAW (MIG) • Gas Metal Arc Welding FCAW (Innershield or Outershield) • Flux Core Arc Welding LF-72/74 BB-2...

  • Page 67: Product Description

    • The K1733-1 and K1733-3 wire straighteners are not compatible with the LF-74 • Gun bushings are required for welding guns that do not have a Magnum (Tweco #2-#4 compatible) back end. • The LF-74 does not attach to K303 or K377 wire reel stands. LF-72/74 BB-3...

  • Page 68: Front Panel Controls And Connections

    Cold Feed - Gas Purge Switch, press the switch up to feed wire with weld output off. Press the switch down for gas flow with weld output off. 2 step - Trigger Interlock switch. Gun Receiver Bushing. Trigger Connector 5-pin amphenol for connecting the MIG gun trigger. See Installation Section for detail. OPERATION DESCRIPTION LF-72/74 BB-4...

  • Page 69: Wire Feed Speed Knob

    Perform regular maintenance and cleaning on the gun liner, conduit and gun. Always use quality electrode, such as L-50 or L-56 from Lincoln Electric. 5. COLD FEED/GAS PURGE SWITCH Cold Feed and Gas Purge are combined into a single spring centered toggle switch.

  • Page 70: Step - Trigger Interlock Switch

    This Gun Receiver Bushing is used with Lincoln gun connectors, also with Magnum 200/300/400 guns and compatible with Tweco® #2-#4). 8. TRIGGER CONNECTOR 5-PIN AMPHENOL This is used for connecting the MIG gun trigger. See Installation Section for detail. LF-72/74 BB-6...
  • Page 71 TABLE OF CONTENTS Section CC-1 Section CC-1 - ACCESSORIES SECTION - Accessories ...Section CC General Options / Accessories...CC-2/CC-5 POWER FEED 10M SINGLE/DUAL...

  • Page 72: Optional Kits

    Includes: Twist-Mate to Twist- Mate, 2/0 Cable for 50' (15.2m) cables. Includes: Lug to Lug, 3/0 Cable of length "xx" for lengths up to 60' (18.3m). Lug to Lug, 4/0 Cable of length "xx" for lengths greater than 60' (18.3m). LF-72/74 CC-2...
  • Page 73 Includes: Gun receiver bush- ing with hose nipple, set screw and hex key wrench. Includes: Gun receiver bush- ing with hose nipple, 4 guide tubes, set screw and hex key wrench. LF-72/74 CC-3...
  • Page 74 2 coil retainers. (Electrode not included.) Includes: Spindle Adapter. Includes: Spindle Adapter. Includes: Readi-Reel spool adapter. (Spool of electrode not included.) Includes: Readi-Reel spool adapter. (Spool of electrode not included.) Includes: 50-60 lb. (22.7 - 27.2 kg) coil adapter. LF-72/74 CC-4...
  • Page 75 Includes: Heavy Duty Wire Reel Stand. Includes: Undercarriage with 8" (203mm) rear wheels, 4" (102mm)casters. Includes: Swivel Platform and Tray. Includes: 2 Swivel Casters, 2 Fixed Casters, brackets and mounting hardware. Includes: Insulated Lift Bail and mounting hardware. LF-72/74 CC-5...
  • Page 76 NOTES CC-6 CC-6 LF-72/74...
  • Page 77 TABLE OF CONTENTS Section DD-1 Section DD-1 - MAINTENANCE SECTION - Maintenance ...Section DD Safety Precautions ...DD-2 Routine Maintenance ...DD-2 Periodic Maintenance ...DD-2 Calibration Specification ...DD-2 Major Component Locations ...DD-4 POWER FEED 10M SINGLE/DUAL...
  • Page 78 9. Connect J2 of the harness to p.c. board. 10. Turn off power to the LF-74 and welding power source. 11. Assemble the wraparound. 12. Connect the electrode lead. LF-72/74 DD-2 TABLE D.1 WFS knob setting TABLE D.2 WIRE LENGTH...
  • Page 79 MAINTENANCE DD-3 DD-3 FIGURE DD.1 FIGURE DD.2 J2 CONNECTOR LF-72/74...
  • Page 80 MAINTENANCE DD-4 DD-4 1. Center Assembly 2. Wire Drive Assembly 3. Wire Reel Stand LF-72 4. Wire Reel Stand LF-74 FIGURE DD.3 - MAJOR COMPONENT LOCATION LF-72/74...
  • Page 81 - THEORY OF OPERATION SECTION - Theory of Operation ...Section E General Description ...E-2 Input Receptacle, Control Board and Operator Controls...E-2 Drive Motor, Tach Feedback and Gas Solenoid...E-3 FIGURE E.1 – LF-72/74 BLOCK LOGIC DIAGRAM 14 PIN INPUT CABLE RECEPTACLE 24/42 VAC...

  • Page 82: Theory Of Operation

    The control board is also responsible for the operation of the trigger interlock, 2-step, cold feed and the gas purge features of the LF72 and the LF74. LF-72/74 SINGLE/DUAL SOLENOID 3.75 AMP OVERLOAD PROTECTION...

  • Page 83: Control Board

    NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion. OPTIONAL OPTIONAL WIRE DRIVE BURNBACK REMOTE RECEPTACLE TIMER VOLTAGE CONTROL CONTROL BOARD TRIGGER WIRE FEED INTERLOCK SPEED POT. 2-STEP LF-72/74 SOLENOID 3.75 AMP OVERLOAD PROTECTION WIRE DRIVE MOTOR TACK To Gun Trigger COLD FEED GAS PURGE...
  • Page 84 NOTES LF-72/74...

  • Page 85: Troubleshooting & Repair Section

    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 TABLE OF CONTENTS LF-72/74 SINGLE/DUAL Section F-1...

  • Page 86: How To Use Troubleshooting Guide

    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 for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877. CAUTION Step 3. PERFORM COMPONENT TESTS. The last column, labeled “Recommended Course of...

  • Page 87: Pc Board Troubleshooting Procedures

    - If the PC board uses protective shorting jumpers, don’t remove them until installation is complete. - If you return a PC board to The Lincoln Electric Company for credit, it must be in the static-shielding bag. This will prevent further damage and allow prop- er failure analysis.

  • Page 88: Function Problems

    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.
  • Page 89 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.
  • Page 90 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. POSSIBLE AREAS OF...

  • Page 91: Drive Motor And Tach Feedback Test

    If for any reason you do not understand the test procedures or are unable to per- form the test / repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 92 9. If the armature voltage is not present (step 5) and the motor operates normally when an isolated power source is applied (step 8) Control board may be faulty. FIGURE F.1 – TACH LEAD LOCATION TACH BLACK WHITE BLACK LEAD LEAD TACH TACH BLUE LF-72/74...

  • Page 93: Gas Solenoid Test

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

  • Page 94: Test Procedure

    12VDC directly to the terminals. If the solenoid does not activate the solenoid is faulty. 9. Reconnect the leads and replace the cover. LF-72/74 F-10 Off = 0 VDC OCV = 59 VDC On = 7.7 VDC 552B If the leads...

  • Page 95: Diode Bridge Test

    If for any reason you do not understand the test procedures or are unable to per- form the test / repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 96 5. Check for the proper output on leads 580 negative and 522 positive. voltage should be 59VDC. only reading 38VDC the control circuit is open. Check the wiring and the connections back to your control board. LF-72/74 F-12 552B 552A If you are...

  • Page 97: Wire Speed Potentiometer Test

    If for any reason you do not understand the test procedures or are unable to per- form the test / repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 98 P8 connection (see wiring diagram), and checking for 0 to 10k ohms between leads 575 and 576 (as pot is located). 7. Reconnect the disconnected leads and reassemble the cover. LF-72/74 F-14 WIRE FEED SPEED CONTROL POTENTIOMETER...

  • Page 99: Pc Board Removal And Replacement

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

  • Page 100: Removal Procedure

    CONTROL BOARD REPLACEMENT PROCEDURE 1. Remove the new control board from the static bag and place it on the 4 studs. 2. Reassemble the 4 nuts and tighten hand tight. 3. Reassemble the harness plugs. 4. Reassemble the case. LF-72/74 F-16...

  • Page 101: Wire Drive Motor And Gear Box

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

  • Page 102: Troubleshooting And Repair

    P10 connector. See wiring diagram. 8. Using the 7/16 inch socket wrench and extension remove the six mounting bolts. See figure F.7. The motor, and gear box assembly can now be removed from the LF72/LF74 unit. LF-72/74 F-18...
  • Page 103 PROCEDURE (Continued) REMOVAL OF THE GEAR BOX FROM THE MOUNTING PANEL. 6. Follow the first five steps found in the drive motor removal. 7. Using the 7/16 wrench remove the four bolts holding the gear box to the panel. LF-72/74 F-19...
  • Page 104 #67 electrode sense lead to the connector block. 9. Using the 3/4 in. wrench connect the electrode lead to the connector block. 10. Connect the gas hose. 11. Install the cover using the five screws. 12. Connect the gun. LF-72/74 F-20...

  • Page 105: Retest After Repair

    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. RETEST AFTER REPAIR SET UP OPERATION VERIFICATION LF-72/74 F-21...
  • Page 106 NOTES F-22 F-22 LF-72/74...

  • Page 107: Electrical Diagrams Section

    Schematic - Common Analog Control PC Board - (G4559 Sheet 1) ...G-10 Schematic - Common Analog Control PC Board - (G4559 Sheet 2) ...G-11 Schematic - Common Analog Control PC Board - (G4559 Sheet 3) ...G-12 PC Board Assembly - Common Analog Control - (G4560-2E0) ...G-13 LF-72/74...
  • Page 108 N.A. TRIGGER INPUT 9 10 1 2 3 4 5 6 7 8 552C CONNECTOR 606A N.B. N.D. THERMAL LED COLD FEED 515A GAS PURGE N.C. 11 12 13 14 15 16 TRIGGER INTERLOCK 2-STEP N.C. N.A. TRIGGER L12146 LF-72/74...

  • Page 109: Electrical Diagrams

    1 2 3 4 5 6 7 8 601 515A 605 606A N.A. TRIGGER INPUT CONNECTOR 606A N.B. N.D. THERMAL LED COLD FEED 515A GAS PURGE N.C. 11 12 13 14 15 16 TRIGGER INTERLOCK 2-STEP N.C. N.A. TRIGGER L12146-1 LF-72/74...

  • Page 110: Wiring Diagram - Entire Machine - Code 11290, 11291, 11292,11293 (L12146-2

    POST-FLOW BURNBACK TIMER KIT (OPTIONAL) 1 2 3 4 5 6 7 8 601 515A 605 606A N.A. N.B. TRIGGER INPUT TRIGGER CONNECTOR 606A N.D. THERMAL LED COLD FEED 515A GAS PURGE N.C. TRIGGER INTERLOCK N.A. 2-STEP N.C. L12146-2 LF-72/74...

  • Page 111: Wiring Diagram - Entire Machine - Code 11195, 11196, 11197, (L12484

    POST-FLOW BURNBACK TIMER KIT (OPTIONAL) 1 2 3 4 5 6 7 8 601 515A 605 606A N.A. N.B. TRIGGER INPUT TRIGGER CONNECTOR 606A N.D. THERMAL LED COLD FEED 515A GAS PURGE N.C. TRIGGER INTERLOCK N.A. 2-STEP N.C. L12484 LF-72/74...

  • Page 112: Schematic - Entire Machine - Code 11075, 11076, 11077 (G4617

    Lights when motor current exceeds 4 Amps for an extended time. Located on Case Front TRIGGER INTERLOCK Located on Case Front Trigger Interlock does not stop welding when the 2-STEP arc is broken. Pull and release to end the weld. LF-72/74...

  • Page 113: Schematic - Entire Machine - Code 11209, 11210, 11211,11227 (G4617-1

    Lights when motor current exceeds 4 Amps for an extended time. Located on Case Front TRIGGER INTERLOCK Located on Case Front Trigger Interlock does not stop welding when the 2-STEP arc is broken. Pull and release to end the weld. LF-72/74...

  • Page 114: Schematic - Entire Machine - Code 11290, 11291, 11292,11293 (G4617-2

    Does NOT operate on 115 VAC. • Lights when motor current exceeds 3.75 Amps for an extended time. Located on Case Front Located on Case Front Trigger Interlock does not stop welding when the arc is broken. Pull and release to end the weld. LF-72/74...

  • Page 115: Schematic - Entire Machine - Code 11195, 11196, 11197, (G4942

    • Lights when motor current exceeds 3.75 Amps for an extended time. Located on Case Front Located on Case Front Trigger Interlock does not stop welding when the arc is broken. Pull and release trigger to end the weld. LF-72/74...

  • Page 116: Schematic - Common Analog Control Pc Board - (G4559 Sheet 1

    G-10 G-10 ELECTRICAL DIAGRAMS SCHEMATIC - COMMON ANALOG CONTROL PC BOARD - (G4559 SHEET 1) NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual. LF-72/74...

  • Page 117: Schematic - Common Analog Control Pc Board - (G4559 Sheet 2

    G-11 G-11 ELECTRICAL DIAGRAMS SCHEMATIC - COMMON ANALOG CONTROL PC BOARD - (G4559 SHEET 2) NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual. LF-72/74...

  • Page 118: Schematic - Common Analog Control Pc Board - (G4559 Sheet 3

    G-12 G-12 ELECTRICAL DIAGRAMS SCHEMATIC - COMMON ANALOG CONTROL PC BOARD - (G4559 SHEET 3) NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual. LF-72/74...

  • Page 119: Pc Board Assembly - Common Analog Control - (G4560-2E0

    Lincoln Electric discourages board level troubleshooting and repair since it may compromise the quality of the design and may result in danger to the Machine Operator or Technician.

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