Lincoln Electric SVM114-C service manual Protective Devices Circuits, Control PC Board Fuses

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E-5

THEORY OF OPERATION

E-5

PROTECTIVE DEVICES AND

CIRCUITS

OVERVOLTAGE SHUTDOWN

If the power source open circuit voltage exceeds about 110-120 volts, the LN-25™ will not operate until the power source voltage drops below about 102-112 volts.

MOTOR OVERLOAD SHUTDOWN

If excessive motor overload occurs (due to prolonged excessive feeding force, jammed drive rolls or shorted motor leads) the LN-25™ will shut down within a few seconds after the overload occurs. The shutdown will reset automatically when the gun trigger is released, but will reoccur if the overload situation is not remedied

CONTROL PC BOARD FUSES

On G1757-2 thru -5 part no. PC boards, the 1/8 amp fuse interrupts the 500A lead to the trigger switch. On G1757-1 PC boards, a 5 amp fuse was used to interrupt the 667 lead. The LN-25™ will not operate if either fuse is blown.

On G1757-6 (or higher) part no. PC boards, the 1/8 amp fuse was replaced with electronic protection for trigger circuit faults to electrode circuit.

LN-25™

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Contents Semiautomatic Wire Feeder California Proposition 65 Warnings SafetyFumes and Gases Electric Shock can killCan be dangerous Cylinder may explode if damaged Welding and Cutting Sparks can Cause fire or explosionIii Sûreté Pour Soudage a L’Arc Précautions DE SûretéMaster Table of Contents for ALL Sections Installation Section Table of ContentsTechnical Specifications LN-25 InstallationWire Feed Speed CurrentrentPower Source Connection Safety PrecautionsGUN Cable Connection to Feeder INVERTEC, CV300 and Other Newer Lincoln Power SourcesWith CV Adapter For GMA GUN and CablesWeld Cable Connection Wire Feed Drive Roll and Guide Tube KitsElectrode Cable Connection Work Cable ConnectionLN-25 Operation Section Welding Capability OperationRead and Understand Entire Section Before Operating Machine Wire Feed Mode Switch Electrode Polarity SwitchWire Speed Dial and Range Switch LN-25 Instruments ControlsWork Clip Lead GAS Post PRE-FLOW Timers OptionalAWG Remote ARC Voltage Control OptionalLoading Electrode Sequence of OperationMounting 22 to 30 LB READI-REELCOILS Mounting 10 to 30 LB SpoolsIdle Roll Pressure Setting Loading Wire DriveGrooves READI-REEL Inside Cage Wires 6OPERATIONB-6Setting Constant Wire Feed Speed CV Mode Presetting Wire Feed SpeedSetting ARC Sensing Wire Feed Speed CC Mode Minimum Arc VoltsMaking a Weld Figure B.4 VV CC Wire Speed SettingWelding Procedure AT END of CoilCylinder may explode if damaged Overvoltage Shutdown Circuit Protection and Automatic ShutdownMotor Overload Shutdown Accessories Section C Accessories SectionLN-25 Option Chart AccessoriesHow to use Table C.1 Table C.1K434-1 GAS Flow Timer KIT Optional AccessoriesGAS Solenoid KIT K430-2 for Codes K432 Remote Control Cable Assembly K433 Power Source Remote BOXRemote Output Control Options and Control Cable Assemblies LN-25 Contactor KIT K443-1 for CodesK625, K626, K627 Remote Control Cable Assembly K439 Remote Extension Cable AssemblyK624-1 42V Remote Output Control Module K444, K444-1 or K444-2 Remote Voltage Control KITTo GUN Switch Connect Leads to Pins a and C Connector Must be Insulated in this AreaStyle a DIA. HoleMaintenance Section Routine Maintenance MaintenanceAdjusting Speed Sensor Module Calibration of LN-25 Wire Speed Dial LN-25 Theory of Operation Section Figure E.1 Theory of Operation Block DiagramTheory of Operation Input Power CircuitGeneral Description Control Circuit OperationTrigger Circuit Feedback and Control CircuitsContactor Optional CircuitsGAS Solenoid Later ModelsControl PC Board Fuses Protective Devices CircuitsLN-25 Troubleshooting and Repair Section HOW to USE Troubleshooting Guide 2TROUBLESHOOTING and REPAIRF-2PC Board Troubleshooting Procedures Troubleshooting and RepairFeeding Problems Feeding Problems Hall Effect Test Description GAS Solenoid Valve and Solenoid PC Board TestMaterials Needed For Codes below 10500 onlyScrew Wire Reel Retaining Collar Test ProcedureCase Door GAS Solenoid ValveFigure F.2 Solenoid Leads Troubleshooting and Repair 512 GAS Solenoid Valve and Solenoid PC Board Test624A 621 J11 PC Board for K430 GAS Solenoid KITLN-25 For Codes Above 10500 only GAS Solenoid Valve and Control PC Board TestFigure F.5 Control BOX Cover Removal For Codes Above 10500 onlyFigure F.6. Solenoid Leads Solenoid LeadsControl PC Board Solenoid Circuitry Test Figure F.7. Applied Voltage Polarity667 555 691 621 500 512 690 G3425LN-25 Hall Effect Module Test G2196 539 541 500 Hall Effect Module Test539 G1757 Figure F.11 Control PC Board Codes Above LN-25 Wire Drive Motor Test Drive Motor Lead IN-LINE Connector Hall Effect Module Contactor & Contactor PC Board Test Contactor & Contactor PC Board Test Contactor Test ProcedureContactor Coil Leads S20963Contactor PC Board Test 28TROUBLESHOOTING and Repair F-28667 J14 LN-25 Tools Required Contactor PC Board ReplacementRepair Procedure Contactor PC Board Replacement33TROUBLESHOOTING and Repair F-33 Figure F.17 Control PC Board Replacement Figure F.21. Control PC Board Codes 9812 and below Control PC Board ReplacementJ14 Figure F.22. Plug Locations for L12253- Control BoardFigure F.24. Control Board Replacement PC Board Screw For Codes below Contactor ReplacementContactor Replacement 40TROUBLESHOOTING and Repair F-40For Codes Above Figure F.26 Phillips Head Screwdriver Wrench Pliers Purge Switch Leads Solenoid Plug J11 Present ReplacementGAS Solenoid Valve AND/OR Solenoid PC Board if GAS SolenoidFigure F.29. Solenoid Assembly Wiring Codes 9812 and below Figure F.31. GAS Solenoid Assembly for Earlier Codes Phillips Head Screwdriver Wrench Slot Head Screwdriver Drive Motor and Gearbox Replacement and Access to 48TROUBLESHOOTING and Repair F-48Hall Effect Module Mylar Insulation Electrode CableG1757 Figure F.34. Drive Motor Replacement Retest After Repair LN-25 Table of Contents Electrical Diagrams Section Electrical DiagramsOptional 42 Volt Remote Output Control Wiring Diagram Above Code 11140 G4679Wiring Diagram Code 10556 Thru 10500 L10925 Wiring Diagram Code 10100 Thru 10500 L9644 Wiring Diagram below Code 9900 L7545 LN-25 Across the ARC Model Schematic Complete Machine Codes Above 11140 G5366Schematic Complete Machine below Code 9900 only G1833 Schematic Control PC BD Above Code 11140 G4616-5 Schematic Control PC BD Code 10556 Thru 10558 G3424-3 Schematic Control PC BD Code 10100 Thru 10500 G2194 L12253 PC Board Assembly Control Abovr Code 11140 L12253-3L12253-3 G3425 PC Board Assembly Control Code 10556 Thru 10558 G3425-3PC Board Assembly Control Code 10100 Thru 10500 G2196-1 LN-25 Control PC Board Assembly Control below Code 9900 G1757-6Contactor Schematic Contactor PC BD Above Code 10500 M10965Schematic Contactor PC BD Code 10100 Thru 10500 M17621 Electrical Diagrams Electrical Diagrams L10863 PC Board Assembly Contactor Above Code 10500 L10863-1PC Board Assembly Contactor Code 10100 Thru 10500 L9670-1 PC Board Assembly Contactor below Code 9900 L9185-2