Lincoln Electric Power MIG 256 Service Manual
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Lincoln Electric Power MIG 256 Service Manual

Lincoln Electric Power MIG 256 Service Manual

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Power MIG
256
®
For use with machines having Code Numbers:
11780, 11781
SERVICE MANUAL
SVM233-A
| Issue D ate 13-Apr
© Lincoln Global, Inc. All Rights Reserved.
NOTE: This manual will cover most of the troubleshooting and repair
procedures for the code numbers listed. Some variances may exist when
troubleshooting/repairing later code numbers.

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  • Page 1 NOTE: This manual will cover most of the troubleshooting and repair procedures for the code numbers listed. Some variances may exist when troubleshooting/repairing later code numbers. Power MIG ® For use with machines having Code Numbers: 11780, 11781 SERVICE MANUAL SVM233-A | Issue D ate 13-Apr ©...
  • Page 2 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 SAFETY ELECTRIC SHOCK can kill. ARC RAYS can burn. 3.a. The electrode and work (or ground) circuits 4.a. Use a shield with the proper filter and cover are electrically “hot” when the welder is on. plates to protect your eyes from sparks and Do not touch these “hot”...
  • Page 4 SAFETY WELDING and CUTTING CYLINDER may explode SPARKS can cause fire or if damaged. explosion. 7.a. Use only compressed cylinders containing the correct shielding gas for the 6.a. Remove fire hazards from the welding area.If process used and properly operating this is not possible, cover them to prevent the welding sparks regulators designed for the gas and from starting a fire.
  • Page 5 SAFETY 6. Eloigner les matériaux inflammables ou les recouvrir afin de PRÉCAUTIONS DE SÛRETÉ prévenir tout risque dʼincendie dû aux étincelles. Pour votre propre protection lire et observer toutes les instructions 7. Quand on ne soude pas, poser la pince à une endroit isolé de et les précautions de sûreté...
  • Page 6 2004/108/EC. It was manufactured in conformity with a national standard that implements a harmonized standard: EN 60974-10 Electromagnetic Compatibility (EMC) Product Standard for Arc Welding Equipment. It is for use with other Lincoln Electric equipment. It is designed for industrial and professional use. Introduction All electrical equipment generates small amounts of electromagnetic emission.
  • Page 7 SAFETY Electromagnetic Compatibility (EMC) The size of the surrounding area to be considered will depend on the structure of the building and other activities that are taking place. The surrounding area may extend beyond the boundaries of the premises. Methods of Reducing Emissions Mains Supply Welding equipment should be connected to the mains supply according to the manufacturerʼs recommen- dations.
  • Page 8 - MASTER TABLE OF CONTENTS FOR ALL SECTIONS - Page Safety ................i-vi Installation .

  • Page 9: Table Of Contents

    TABLE OF CONTENTS - INSTALLATION SECTION Installation ................A-1 Technical Specifications .
  • Page 10 INSTALLATION TECHNICAL SPECIFICATIONS – POWER MIG ® INPUT – SINGLE PHASE ONLY STANDARD INPUT CURRENT @ 200 AMP INPUT CURRENT @ 250 AMP VOLTAGE/PHASE/FREQUENCY RATED OUTPUT RATED OUTPUT 208/230/1/60 Hz *47/44 Amps *56/52 Amps 230/460/575/1/60 Hz 41/20/16 Amps 47/24/19 Amps RATED OUTPUT DUTY CYCLE AMPS...

  • Page 11: Installation

    INSTALLATION INPUT POWER, GROUNDING AND Read entire installation section before starting installation. CONNECTION DIAGRAM SAFETY PRECAUTIONS WARNING WARNING ELECTRIC SHOCK can kill. ELECTRIC SHOCK can kill. • Do not touch electrically live parts such as output terminals or inter- • Only qualified personnel should nal wiring.

  • Page 12: Output Polarity Connections

    INSTALLATION 3. The 208/230 volt 60 Hz model POWER MIG is OUTPUT POLARITY CONNECTIONS shipped with a 10 ft. input cable and plug connect- The welder, as shipped from the factory, is connected ed to the welder. Obtain a receptacle and mount it for electrode positive (+) polarity.

  • Page 13: Shielding Gas

    INSTALLATION 3. Stand to one side away from the outlet and open SHIELDING GAS the cylinder valve for an instant. This blows away [For Gas Metal Arc Welding(GMAW) Processes] any dust or dirt which may have accumulated in the valve outlet. Customer must provide cylinder of appropriate type shielding gas for the process being used.

  • Page 14: Auxiliary Power Receptacles

    INSTALLATION AUXILIARY POWER RECEPTACLES (For 208/230V Models only) This machine is equipped with 15Amp 120V receptacle with 15Amp Circuit Breaker. The receptacle is UL and CSA approved. COIL CLAW™ INSTALLATION The Coil Claw™ and mounting screws are provided as an optional accessory for the POWER MIG 256.
  • Page 15 TABLE OF CONTENTS - OPERATION SECTION Operation ................B-1 Safety Precautions .

  • Page 16: Operation

    OPERATION Read entire Operation section before operating the POWER MIG 256. ® SAFETY PRECAUTIONS WARNING ELECTRIC SHOCK can kill. • Do not touch electrically live parts or electrode with skin or wet cloth- ing. Insulate yourself from work and ground. •...

  • Page 17: Product Description

    OPERATION LIMITATIONS PRODUCT DESCRIPTION The POWER MIG 256 is a complete semiautomatic POWER MIG ® 256 WILL NOT operate satisfactorily if ® powered with a portable or in-plant generating system. constant voltage DC arc welding machine built to meet NEMA specifications. It combines a constant voltage DESCRIPTION OF CONTROLS power source and a constant speed wire feeder with a microcomputer-based controller to form a reliable high-...

  • Page 18: Wire Size Conversion Parts

    OPERATION The drive rolls installed with the POWER MIG To make spot plug welds, punch 3/16" (5 mm) holes ® have two grooves one for .035(0.9mm) wire Solid Steel in the top sheet. Set the Spot Time control to approximately 1.2 seconds and set the procedure electrode and the other for .045(1.1mm) wire.

  • Page 19: Wire Reel Loading - Readi Reels, Spools Or Coils

    OPERATION WIRE REEL LOADING - READI FIGURE B.3 REELS, SPOOLS OR COILS ADAPTER 2 IN. O.D. SPINDLE RETAINING SPRING To Mount a 30 Lb. (14 kg) Readi-Reel Package (Using the Molded Plastic K363-P Readi-Reel Adapter): RETAINING (Items 1-10, See Figure B.3) COLLAR 1.

  • Page 20: Feeding Wire Electrode

    OPERATION FEEDING WIRE ELECTRODE IDLE ROLL PRESSURE SETTING WARNING WARNING When triggering, the electrode and drive mecha- ELECTRIC SHOCK can kill. nism are electrically "hot" relative to work and • Turn the input power OFF at the ground and remain "hot" several seconds after the welding power source before gun trigger is released.

  • Page 21: Wire Drive Configuration

    OPERATION WIRE DRIVE CONFIGURATION 1. Turn power off at the welding power source. 2. Remove the welding wire from the wire drive. (Items 1-11, See Figure B.5) 3. Remove the thumb screw from the wire drive. CHANGING THE GUN RECEIVER 4.

  • Page 22: Making A Weld

    OPERATION MAKING A WELD 8. Position electrode over joint. End of electrode may be lightly touching the work. 1. Check that the electrode polarity is correct for the 9. Lower welding helmet, close gun trigger and begin process being used, then turn the power switch ON. welding.

  • Page 23: Input Line Voltage Protection

    OPERATION INPUT LINE VOLTAGE WELDING THERMAL OVERLOAD PROTECTION PROTECTION The POWER MIG 256 has built-in protective ther- High Line Voltage - If the line voltage exceeds 125% ® mostats that respond to excessive temperature. They of rated input voltage, the output will be reduced to the lower level to protect voltage rating of the capacitor open the wire feed and welder output circuits if the machine exceeds the maximum safe operating tem-...
  • Page 24 NOTES B-10 B-10 Power MIG ®...
  • Page 25 TABLE OF CONTENTS - ACCESSORIES SECTION Accessories ................C-1 Drive Roll Kits .

  • Page 26: Accessories

    ACCESSORIES ALTERNATIVE MAGNUM GMAW DRIVE ROLL KITS GUN AND CABLE ASSEMBLIES See Table C.1 for various drive roll kits that are avail- able for the POWER MIG 256. The item in Bold is ® The following Magnum PRO 250L gun and cable ®...

  • Page 27: Connecting The Spool Gun To The Power Mig ® 256

    ACCESSORIES CONNECTING THE SPOOL GUN TO CAUTION THE POWER MIG ® Closing either gun trigger will cause the electrode (Items 1-4, See Figure C.1) of both guns to be electrically "HOT". Be sure 1. Connect the Spool Gun control cable to the mating unused gun is positioned so electrode or tip will 7-pin receptacle in the Power MIG wire drive com- not contact metal case or other metal common to...

  • Page 28: Making A Weld With The Magnum Sg Spool Gun

    ACCESSORIES See the following procedure for setting the Wire Speed 4. The following procedure settings for Aluminum 4043 can be used as initial settings for making test Feed using the Magnum SG Spool Gun: welds to determine final settings: WIRE FEED SG SPOOL GUN WIRE FEED SPEED WIRE DIAMETER WIRE FEED...
  • Page 29 TABLE OF CONTENTS - MAINTENANCE SECTION Maintenance ................D-1 Safety Precautions .
  • Page 30 MAINTENANCE SAFETY PRECAUTIONS CONTACT TIP AND GAS NOZZLE INSTALLATION WARNING 1. Choose the correct size contact tip for the electrode being used (wire size is stenciled on the side of the ELECTRIC SHOCK can kill. contact tip) and screw it snugly into the gas diffuser. •...
  • Page 31 MAINTENANCE LINER REMOVAL AND 7. Screw the gas diffuser onto the end of the gun tube and securely tighten. REPLACEMENT 8. Tighten the set screw in the side of the gas diffuser NOTE: Changing the liner for a different wire size against the cable liner using a 5/64"...
  • Page 32 MAINTENANCE FIGURE D.3 - MAJOR COMPONENT LOCATIONS 1. Case Front Assembly 2. Case Back Assembly 3. Center Assembly 4. Wire Dive Assembly 5. Base & Power Component Assembly 6. Covers Assembly 7. Gun & Cable Assembly (Magnum Pro 250L) ® Power MIG ®...
  • Page 33 TABLE OF CONTENTS-THEORY OF OPERATION SECTION Theory of Operation ..............E-1 Input Line Voltage And Main Transformer .
  • Page 34 THEORY OF OPERATION FIGURE E.2 - INPUT LINE VOLTAGE AND MAIN TRANSFORMER SPOOL GUN SOLENOID SPOOL DIGITAL SOLENOID MOTOR WIRE DISPLAYS DRIVE MOTOR WIRE SPEED CONTROL BOARD VOLTAGE TACH TIMER ASSEMBLY 115 VAC GUN TRIGGER RECTIFIER DIODE FEEDBACK BRIDGE 30 VAC LINE SWITCH POWER FACTOR...
  • Page 35 THEORY OF OPERATION FIGURE E.3 - OUTPUT RECTIFICATION AND FEEDBACK CONTROL SPOOL GUN SOLENOID SPOOL DIGITAL SOLENOID MOTOR WIRE DISPLAYS DRIVE MOTOR WIRE SPEED CONTROL BOARD VOLTAGE TACH TIMER ASSEMBLY 115 VAC GUN TRIGGER RECTIFIER DIODE FEEDBACK BRIDGE 30 VAC LINE SWITCH POWER FACTOR...
  • Page 36 THEORY OF OPERATION FIGURE E.4 - CONSTANT VOLTAGE OUTPUT SPOOL GUN SOLENOID SPOOL DIGITAL SOLENOID MOTOR WIRE DISPLAYS DRIVE MOTOR WIRE SPEED CONTROL BOARD VOLTAGE TACH TIMER ASSEMBLY 115 VAC GUN TRIGGER RECTIFIER DIODE FEEDBACK BRIDGE 30 VAC LINE SWITCH POWER FACTOR OUTPUT POSITIVE...
  • Page 37 THEORY OF OPERATION FIGURE E.5 - WIRE DRIVE MOTOR AND FEEDBACK SPOOL GUN SOLENOID SPOOL DIGITAL SOLENOID MOTOR WIRE DISPLAYS DRIVE MOTOR WIRE SPEED CONTROL BOARD VOLTAGE TACH TIMER ASSEMBLY 115 VAC GUN TRIGGER RECTIFIER DIODE FEEDBACK BRIDGE 30 VAC LINE SWITCH POWER FACTOR...
  • Page 38 THEORY OF OPERATION THERMAL AND OVERLOAD OVERCURRENT PROTECTION PROTECTION The machine will automatically reduce the output if the load on the machine exceeds 300 to 320 amperes. The Power MIG ® 256 has built-in protective ther- This protects the welding power SCRs from excessive mostats that respond to excessive temperatures.
  • Page 39 THEORY OF OPERATION FIGURE E.6 - SCR OPERATION INPUT CATHODE OUTPUT NOTE: AS THE GATE PULSE IS APPLIED ANODE LATER IN THE CYCLE THE SCR OUTPUT IS DECREASED. GATE SCR OPERATION A silicon controlled rectifier (SCR) is a three terminal An SCR is fired by a short burst of current into the gate.
  • Page 40 NOTES Power MIG ®...
  • Page 41 TABLE OF CONTENTS - TROUBLESHOOTING AND REPAIR Troubleshooting and Repair ............. .F-1 How to Use Troubleshooting Guide .

  • Page 42: How To Use Troubleshooting Guide

    HOW TO USE TROUBLESHOOTING GUIDE WARNING Service and Repair should only be performed by Lincoln Electric Factory Trained Personnel. Unauthorized repairs performed on this equipment may result in danger to the technician and machine operator and will invalidate your factory warranty. For your safety and to avoid Electrical Shock, please observe all safety notes and precautions detailed throughout this manual.

  • Page 43: Pc Board Troubleshooting Procedures

    Do not touch electrically hot parts. - 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- CAUTION er failure analysis.
  • Page 44 CAUTION If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact the Lincoln Electric Service Department for technical troubleshooting assistance before you proceed. Call 1-888-935-3877. Power MIG ®...
  • Page 45 5. The control board may be faulty. Replace. CAUTION If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact the Lincoln Electric Service Department for technical troubleshooting assistance before you proceed. Call 1-888-935-3877. Power MIG ®...
  • Page 46 CAUTION If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact the Lincoln Electric Service Department for technical troubleshooting assistance before you proceed. Call 1-888-935-3877. Power MIG ®...
  • Page 47 OFF. Replace. CAUTION If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact the Lincoln Electric Service Department for technical troubleshooting assistance before you proceed. Call 1-888-935-3877. Power MIG ®...
  • Page 48 Electric Authorized Field Service Facility. CAUTION If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact the Lincoln Electric Service Department for technical troubleshooting assistance before you proceed. Call 1-888-935-3877. Power MIG ®...
  • Page 49 2. The control board may be faulty. Replace. CAUTION If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact the Lincoln Electric Service Department for technical troubleshooting assistance before you proceed. Call 1-888-935-3877. Power MIG ®...
  • Page 50 2. The control board may be faulty. Replace. CAUTION If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact the Lincoln Electric Service Department for technical troubleshooting assistance before you proceed. Call 1-888-935-3877. Power MIG ®...

  • Page 51: Main Transformer Test

    MAIN TRANSFORMER TEST WARNING Service and repair should be performed only by Lincoln Electric factory trained personnel. Unauthorized repairs performed on this equipment may result in danger to the technician or machine operator and will invalidate your factory warranty. For your safety and to avoid electrical shock, please observe all safety notes and precautions detailed throughout this manual.
  • Page 52 TROUBLESHOOTING AND REPAIR F-12 F-12 MAIN TRANSFORMER TEST (continued) FIGURE F.1 – G4824 CONTROL PC BOARD MAIN TRANSFORMER TEST POINTS (6J6) (5J6) (4J6) (8J5) #206 (16J5) (3J5) #208 (2J5) #209 (1J5) PROCEDURE 1. Disconnect the main input power supply to the WARNING machine.
  • Page 53 TROUBLESHOOTING AND REPAIR F-13 F-13 MAIN TRANSFORMER TEST (continued) 5. Connect main input power to the machine. 13. Locate the following leads at plug J5 on the Control PC board. See Figure F.1. 6. Turn the Power MIG ® 256 ON/OFF power switch to ON.
  • Page 54 NOTES F-14 F-14 Power MIG ®...

  • Page 55: Rectifier Diode Bridge Test

    RECTIFIER DIODE BRIDGE TEST WARNING Service and repair should be performed only by Lincoln Electric factory trained personnel. Unauthorized repairs performed on this equipment may result in danger to the technician or machine operator and will invalidate your factory warranty. For your safety and to avoid electrical shock, please observe all safety notes and precautions detailed throughout this manual.
  • Page 56 TROUBLESHOOTING AND REPAIR F-16 F-16 RECTIFIER DIODE BRIDGE TEST (continued) FIGURE F.2 – RECTIFIER DIODE BRIDGE LOCATION RECTIFIER BRIDGE (D2) PROCEDURE WARNING 3. Perform the Main Transformer Test to ensure the proper voltages are supplied to the J5 plug on the Control board. ELECTRIC SHOCK can kill.
  • Page 57 TROUBLESHOOTING AND REPAIR F-17 F-17 RECTIFIER DIODE BRIDGE TEST (continued) 6. Turn the Power MIG ® 256 ON/OFF POWER SWITCH to ON. 7. Carefully make the following voltage tests: a. Turn the machine OFF between each test. b. Carefully connect the meter plugs to the exposed lead connections.
  • Page 58 NOTES F-18 F-18 Power MIG ®...

  • Page 59: Static Scr Rectifier Assembly Test

    STATIC SCR RECTIFIER ASSEMBLY TEST WARNING Service and repair should be performed only by Lincoln Electric factory trained personnel. Unauthorized repairs performed on this equipment may result in danger to the technician or machine operator and will invalidate your factory warranty. For your safety and to avoid electrical shock, please observe all safety notes and precautions detailed throughout this manual.
  • Page 60 TROUBLESHOOTING AND REPAIR F-20 F-20 STATIC SCR RECTIFIER ASSEMBLY TEST (continued) FIGURE F.3 – REMOVE PLUGS J6 AND J5 TO PERFORM STATIC RECTIFIER ASSEMBLY TEST PROCEDURE WARNING 1. Disconnect main AC input power to the machine. 2. Using a 3/8“ nutdriver, remove the case top and ELECTRIC SHOCK can kill.
  • Page 61 TROUBLESHOOTING AND REPAIR F-21 F-21 STATIC SCR RECTIFIER ASSEMBLY TEST (continued) FIGURE F.4 – LEADS X2 AND X3 LEAD LOCATION FIGURE F.5 – SCR 1 TEST POINTS NEGATIVE CAPACITOR BANK BUSS LEADS X2 AND X3 CONNECTION 5. Locate the braided copper strap that connects 8.
  • Page 62 NOTES F-22 F-22 Power MIG ®...

  • Page 63: Active Scr Rectifier Assembly Test

    ACTIVE SCR RECTIFIER ASSEMBLY TEST WARNING Service and repair should be performed only by Lincoln Electric factory trained personnel. Unauthorized repairs performed on this equipment may result in danger to the technician or machine operator and will invalidate your factory warranty. For your safety and to avoid electrical shock, please observe all safety notes and precautions detailed throughout this manual.
  • Page 64 TROUBLESHOOTING AND REPAIR F-24 F-24 ACTIVE SCR RECTIFIER ASSEMBLY TEST (continued) FIGURE F.6 – CONTROL BOARD MOLEX PLUG LOCATIONS FOR G4824 PC CONTROL BOARD PROCEDURE 1. Disconnect main AC input power to the WARNING machine. 2. Using a 3/8“ nutdriver, remove the case top and ELECTRIC SHOCK can kill.
  • Page 65 TROUBLESHOOTING AND REPAIR F-25 F-25 ACTIVE SCR RECTIFIER ASSEMBLY TEST (continued) FIGURE F.7 – LEADS X2 AND X3 LOCATION FIGURE F.8 – SCR TESTER CIRCUIT AND SCR CONNECTIONS NEGATIVE CAPACITOR BANK BUSS LEADS X2 AND X3 CONNECTION 5. Locate the braided copper strap that connects transformer secondary winding conductors X2 and X3 to the negative capacitor buss bar.
  • Page 66 TROUBLESHOOTING AND REPAIR F-26 F-26 ACTIVE SCR RECTIFIER ASSEMBLY TEST (continued) 7. Connect the tester to the SCR 1 as shown in 12. Open switch SW-1. Figure F.8. 13. Reconnect the tester leads. See Figure F.8. a. Connect tester lead (A) to the anode. a.

  • Page 67: Wire Drive Motor And Tachometer Feedback Test

    WIRE DRIVE MOTOR AND TACHOMETER FEEDBACK TEST WARNING Service and repair should be performed only by Lincoln Electric factory trained personnel. Unauthorized repairs performed on this equipment may result in danger to the technician or machine operator and will invalidate your factory warranty. For your safety and to avoid electrical shock, please observe all safety notes and precautions detailed throughout this manual.
  • Page 68 TROUBLESHOOTING AND REPAIR F-28 F-28 WIRE DRIVE MOTOR AND TACHOMETER FEEDBACK TEST (continued) FIGURE F.9 – PLUG J1 LOCATION ON CONTROL PC BOARD (4J1) #555 (2J1) (6J1) #515B #206B (5J1) (1J1) PROCEDURE Test for Correct Wire Drive Motor Armature WARNING Voltage 1.
  • Page 69 TROUBLESHOOTING AND REPAIR F-29 F-29 WIRE DRIVE MOTOR AND TACHOMETER FEEDBACK TEST (continued) 7. Make the following voltage tests: TEST FOR SUPPLY VOLTAGE TO TACHOMETER a. Turn the machine OFF between each test. 1. Disconnect the main AC input power to the b.
  • Page 70 TROUBLESHOOTING AND REPAIR F-30 F-30 WIRE DRIVE MOTOR AND TACHOMETER FEEDBACK TEST (continued) TEST FOR FEEDBACK VOLTAGE TO CONTROL BOARD 1. Disconnect the main AC input power to the 6. If the 1.5 to 3.5 VDC is present, the tachometer machine. circuit is sending the correct feedback signal to the Control PC Board.

  • Page 71: Normal Open Circuit Voltage Waveform

    TROUBLESHOOTING AND REPAIR F-31 F-31 NORMAL OPEN CIRCUIT VOLTAGE WAVEFORM 0 volts 2.5 ms 20.0 V This is the typical open circuit weld output voltage generated from a prop- erly operating machine. Note that each vertical division represents 20 volts and that each horizontal division represents 2.5 milliseconds in time.

  • Page 72: Typical Voltage Waveform - Machine Loaded

    TROUBLESHOOTING AND REPAIR F-32 F-32 TYPICAL VOLTAGE WAVEFORM - MACHINE LOADED 0 volts 5 ms 20.0 V This is the typical weld output voltage generated from a properly operating machine with a load applied. Note that each vertical division represents 20 volts and that each horizontal division represents 5 milliseconds in time.

  • Page 73: Abnormal Output Voltage Waveform - Machine Loaded

    TROUBLESHOOTING AND REPAIR F-33 F-33 ABNORMAL OUTPUT VOLTAGE WAVEFORM - MACHINE LOADED ONE OUTPUT SCR NOT FUNCTIONING 0 volts 20.0 V This is NOT a typical DC output volt- age waveform. One output SCR is not functioning. Note the increased ripple content.

  • Page 74: Abnormal Open Circuit Voltage

    TROUBLESHOOTING AND REPAIR F-34 F-34 ABNORMAL OPEN CIRCUIT VOLTAGE OUTPUT CAPACITOR BANK NOT FUNCTIONING 0 volts 20.0 V 5 ms This is NOT the typical DC output volt- age waveform. The output capacitors are not functioning. Note the lack of “filtering”...

  • Page 75: Typical Scr Gate Voltage Waveform

    TROUBLESHOOTING AND REPAIR F-35 F-35 TYPICAL SCR GATE VOLTAGE WAVEFORM 0 volts 2.00 V 5 ms This is a typical SCR gate pulse voltage waveform. The machine was in an open circuit condition (no load) and operating properly. Note that each vertical division represents 2 volts and each horizontal division represents 5 milliseconds in time.
  • Page 76 NOTES F-36 F-36 Power MIG ®...
  • Page 77 REMOVAL AND REPLACEMENT PROCEDURE WARNING Service and repair should be performed only by Lincoln Electric factory trained personnel. Unauthorized repairs performed on this equipment may result in danger to the technician or machine operator and will invalidate your factory warranty. For your safety and to avoid electrical shock, please observe all safety notes and precautions detailed throughout this manual.
  • Page 78 TROUBLESHOOTING AND REPAIR F-38 F-38 CONTROL PC BOARD REMOVAL AND REPLACEMENT PROCEDURE (continued) FIGURE F.10 – WIRING HARNESS AND MOLEX PLUG LOCATIONS REMOVAL PROCEDURE 1. Disconnect main input power to the machine. WARNING 2. Using a 3/8” nutdriver, remove the case top, side and door assembly.

  • Page 79: Control Pc Board Removal And Replacement Procedure

    TROUBLESHOOTING AND REPAIR F-39 F-39 CONTROL PC BOARD REMOVAL AND REPLACEMENT PROCEDURE (continued) FIGURE F.11 – CONTROL BOARD MOUNTING CONTROL PC BOARD REPLACEMENT PROCEDURE 1. Carefully place the new Control PC board into position in the machine. 2. Carefully secure board to mounting standoffs. 3.
  • Page 80 NOTES F-40 F-40 Power MIG ®...

  • Page 81: Wire Drive Assembly Removal And Replacement Procedure

    REMOVAL AND REPLACEMENT PROCEDURE WARNING Service and repair should be performed only by Lincoln Electric factory trained personnel. Unauthorized repairs performed on this equipment may result in danger to the technician or machine operator and will invalidate your factory warranty. For your safety and to avoid electrical shock, please observe all safety notes and precautions detailed throughout this manual.
  • Page 82 TROUBLESHOOTING AND REPAIR F-42 F-42 WIRE DRIVE ASSEMBLY REMOVAL AND REPLACEMENT PROCEDURE (continued) FIGURE F.12 – LEAD AND HEX HEAD SCREW LOCATIONS WIRE DRIVE ASSEMBLY LEAD HEX HEAD SCREW REMOVAL PROCEDURE 5. Using a 3/4” wrench, remove the hex head WARNING screw and lead from the wire drive assembly.
  • Page 83 TROUBLESHOOTING AND REPAIR F-43 F-43 WIRE DRIVE ASSEMBLY REMOVAL AND REPLACEMENT PROCEDURE (continued) FIGURE F.13 – OUTER & INNER WIRE GUIDE ADJUSTMENT ARM ASSEMBLY INNER WIRE GUIDE OUTER WIRE GUIDE WIRE DRIVE COMPARTMENT GEARBOX MOUNTING PANEL 11. Remove the hex nuts securing the gearbox 15.
  • Page 84 TROUBLESHOOTING AND REPAIR F-44 F-44 WIRE DRIVE ASSEMBLY REMOVAL AND REPLACEMENT PROCEDURE (continued) FIGURE F.14 – DRIVE ROLL SHAFT ASSEMBLY ADJUSTMENT ARM ASSEMBLY DRIVE ROLL SHAFT ASSEMBLY TWIST LOCK RING DRIVE HUB RETAINERS FIGURE F.15 – DRIVE GEAR REMOVAL LOCK WASHER PHILLIPS SCREW...
  • Page 85 TROUBLESHOOTING AND REPAIR F-45 F-45 WIRE DRIVE ASSEMBLY REMOVAL AND REPLACEMENT PROCEDURE (continued) FIGURE F.16 – MOTOR GEARBOX ASSEMBLY MOTOR GEARBOX ASSEMBLY REPLACEMENT PROCEDURE 9. Install the gearbox mounting panel, motor gear- box assembly and wire drive assembly. 1. Carefully position the new wire drive assembly careful the wires do not catch while replacing it.
  • Page 86 NOTES F-46 F-46 Power MIG ®...

  • Page 87: Scr Output Removal And Replacement Procedure

    SCR OUTPUT REMOVAL AND REPLACEMENT PROCEDURE WARNING Service and repair should be performed only by Lincoln Electric factory trained personnel. Unauthorized repairs performed on this equipment may result in danger to the technician or machine operator and will invalidate your factory warranty. For your safety and to avoid electrical shock, please observe all safety notes and precautions detailed throughout this manual.
  • Page 88 TROUBLESHOOTING AND REPAIR F-48 F-48 SCR OUTPUT REMOVAL AND REPLACEMENT PROCEDURE (continued) FIGURE F.17 – LEFT HEAT FIGURE F.18 – MIDDLE HEAT SINK LEAD DISCONNECTION SINK LEAD DISCONNECTION LEFT HEAT SINK GATE LEADS G1 AND G2 LEAD X1 HEAVY MIDDLE LEADS #208 AND #208R LEAD...
  • Page 89 TROUBLESHOOTING AND REPAIR F-49 F-49 SCR OUTPUT REMOVAL AND REPLACEMENT PROCEDURE (continued) FIGURE F.19 – RIGHT HEAT SINK LEAD DISCONNECTION Power MIG ®...
  • Page 90 TROUBLESHOOTING AND REPAIR F-50 F-50 SCR OUTPUT REMOVAL AND REPLACEMENT PROCEDURE (continued) REPLACEMENT PROCEDURE NOTE: When installing the SCR rectifier assembly, 6. Using a 1/2” socket and 3/8” open end wrench, apply a thin coating of Dow Corning #340 connect the SCR diode lead to the negative compound to the electrical connections.

  • Page 91: Capacitor Bank Removal And Replacement Procedure

    CAPACITOR BANK REMOVAL AND REPLACEMENT PROCEDURE WARNING Service and repair should be performed only by Lincoln Electric factory trained personnel. Unauthorized repairs performed on this equipment may result in danger to the technician or machine operator and will invalidate your factory warranty. For your safety and to avoid electrical shock, please observe all safety notes and precautions detailed throughout this manual.
  • Page 92 TROUBLESHOOTING AND REPAIR F-52 F-52 CAPACITOR BANK REMOVAL AND REPLACEMENT PROCEDURE (continued) REMOVAL PROCEDURE REPLACEMENT PROCEDURE WARNING 1. Clear the leads and carefully position the capacitor bank assembly into the machine. ELECTRIC SHOCK can kill. 2. Using a 3/8” nutdriver, connect the three nuts securing the capacitor bank to the bottom of the machine.
  • Page 93 TROUBLESHOOTING AND REPAIR F-53 F-53 CAPACITOR BANK REMOVAL AND REPLACEMENT PROCEDURE (continued) FIGURE F.20 – CAPACITOR BANK COMPONENT LOCATIONS Power MIG ®...
  • Page 94 NOTES F-54 F-54 Power MIG ®...

  • Page 95: Main Transformer And Output Choke Removal And Replacement Procedure

    REMOVAL AND REPLACEMENT PROCEDURE WARNING Service and repair should be performed only by Lincoln Electric factory trained personnel. Unauthorized repairs performed on this equipment may result in danger to the technician or machine operator and will invalidate your factory warranty. For your safety and to avoid electrical shock, please observe all safety notes and precautions detailed throughout this manual.
  • Page 96 TROUBLESHOOTING AND REPAIR F-56 F-56 MAIN TRANSFORMER AND OUTPUT CHOKE REMOVAL AND REPLACEMENT PROCEDURE (continued) FIGURE F.21 – MAIN TRANSFORMER REMOVAL LEAD OUTPUT CHOKE OUTPUT LEAD CHOKE POSITIVE LEAD NOTE: PLUG-IN LEADS ARE NOT SHOWN FOR CLARITY. LEAD LEADS X2 AND X3 MAIN TRANSFORMER POWER...
  • Page 97 TROUBLESHOOTING AND REPAIR F-57 F-57 MAIN TRANSFORMER AND OUTPUT CHOKE REMOVAL AND REPLACEMENT PROCEDURE (continued) 11. Unplug and label leads X5, X6, X7, X8 and X9. REPLACEMENT PROCEDURE These leads have connectors near the trans- 1. Carefully position the new main transformer former which can be disconnected.
  • Page 98 NOTES F-58 F-58 Power MIG ®...
  • Page 99 REMOVAL AND REPLACEMENT PROCEDURE WARNING Service and repair should be performed only by Lincoln Electric factory trained personnel. Unauthorized repairs performed on this equipment may result in danger to the technician or machine operator and will invalidate your factory warranty. For your safety and to avoid electrical shock, please observe all safety notes and precautions detailed throughout this manual.
  • Page 100 TROUBLESHOOTING AND REPAIR F-60 F-60 FAN MOTOR ASSEMBLY REMOVAL AND REPLACEMENT PROCEDURE (continued) FIGURE F.22 – FAN MOTOR ASSEMBLY BLADE LEAD #353 BLADE LEAD CLAMP #352 MOTOR REMOVAL PROCEDURE 3. Disconnect the fan motor leads 352 and 353. WARNING See Figure F.22. 4.
  • Page 101 TROUBLESHOOTING AND REPAIR F-61 F-61 FAN MOTOR ASSEMBLY REMOVAL AND REPLACEMENT PROCEDURE (continued) REPLACEMENT PROCEDURE 1. When installing the new fan motor assembly 3. Install the fan blade. ensure the fan is installed on the shaft in the a. Carefully position the fan blade on to the same position as prior to removal.
  • Page 102 TROUBLESHOOTING AND REPAIR F-62 F-62 RETEST AFTER REPAIR INPUT IDLE AMPS AND WATTS INPUT VOLTS/HERTZ MAXIMUM IDLE AMPS MAXIMUM IDLE WATTS 230/60 OPEN CIRCUIT VOLTAGE 35-40 VDC WIRE SPEED RANGE 50-700 IPM (1.27-17.8 m/minute) Power MIG ®...
  • Page 103 TABLE OF CONTENTS - DIAGRAM SECTION Electrical Diagrams ..............G-1 Wiring Diagram - Code 11780 (L12464-2) .
  • Page 104 ElECTriCal DiaGramS WiriNG DiaGram - COmplETE maChiNE - CODE 11780 (l12464-2) POWER MIG 256 (208/230V) NOTES: DISPLAY GENERAL INFORMATION BOARD N.A. WELDING CABLE MUST BE OF PROPER CAPACITY FOR THE ELECTRICAL SYMBOLS PER E1537 CONTROL BOARD CURRENT AND DUTY CYCLE OF IMMEDIATE AND CAVITY NUMBERING SEQUENCE FUTURE APPLICATIONS.
  • Page 105 ElECTriCal DiaGramS WiriNG DiaGram - COmplETE maChiNE - CODE 11781 (l12506-2) POWER MIG 256 (230/460/575V) NOTES: DISPLAY GENERAL INFORMATION BOARD N.A. WELDING CABLE MUST BE OF PROPER CAPACITY FOR THE ELECTRICAL SYMBOLS PER E1537 CONTROL BOARD CURRENT AND DUTY CYCLE OF IMMEDIATE AND CAVITY NUMBERING SEQUENCE FUTURE APPLICATIONS.
  • Page 106 ElECTriCal DiaGramS SChEmaTiC - COmplETE maChiNE (G4752-2) NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual. pOWEr miG ®...
  • Page 107 ElECTriCal DiaGramS SChEmaTiC - WElD CONTrOl pC BOarD (G4823-2F3) (pG 1) NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual. pOWEr miG ®...
  • Page 108 ElECTriCal DiaGramS SChEmaTiC - WElD CONTrOl pC BOarD (G4823-2F3) (pG 2) NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual. pOWEr miG ®...
  • Page 109 ElECTriCal DiaGramS SChEmaTiC - WElD CONTrOl pC BOarD (G4823-2F3) (pG 3) NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual. pOWEr miG ®...
  • Page 110 ElECTriCal DiaGramS SChEmaTiC - DiSplaY pC BOarD (l10951) CONVERTED FROM MICROSTATION ENGINEERING CONTROLLED CHANGE DETAIL: MANUFACTURER: BANK4 BANK3 BANK2 BANK1 BANK5 DISP3 DISP2 DISP1 DATA IN CLOCK /ENABLE DATA OUT MC14489 LATCH .0047 .0047 BANK4 BANK3 VOLTS BANK2 MOSI BANK1 LED3 BANK5 DISP7...
  • Page 111 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.
  • Page 112 G-10 G-10 ElECTriCal DiaGramS SChEmaTiC - TimEr pC BOarD (m19281) NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual. pOWEr miG ®...
  • Page 113 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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