Lincoln Electric SP-100 service manual Output CONTROL, RECTIFICA- Tion and Voltage Feedback

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THEORY OF OPERATION

E-2

FIGURE E.2 – Output Circuits

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OUTPUT CONTROL, RECTIFICA- TION AND VOLTAGE FEEDBACK

The AC voltage that is applied to the main transformer primary is controlled at the con- trol board by two SCR’s (Silicon Controlled Rectifiers). The SCR’s are controlled by a pulse signal developed on the control board. The control board compares the commands of the arc voltage control with the voltage feedback signal. The board circuitry then sends a pulse to turn on the SCR’s. In this manner, the voltage applied to the primary of the transformer is varied and controlled. This variable and controlled voltage is

reflected at the transformer secondary wind- ing and is applied to the rectifier diode bridge. This rectified DC voltage is filtered by the output capacitor and choke circuit and is applied to the machine’s output ter- minals.

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NOTE: Unshaded areas of block logic diagram are the subject of discussion.

SP-100

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Contents SP-100 Electric Shock can kill SafetyARC Rays can burn Fumes and Gases can be dangerousWelding Sparks can cause fire or explosion Cylinder may explode if damagedMay be dangerous Electric and Magnetic FieldsSûreté Pour Soudage a L’Arc Précautions DE SûretéMaster Table of Contents for ALL Sections Installation Section Table of ContentsTechnical Specifications SP-100 InstallationRead entire installation section before starting Safety PrecautionsInstallation Identify and Locate ComponentsSelect Suitable Location Work Clamp InstallationOutput Connections TiltingGUN Installation Connecting GUN Cable to the SP-100GAS Connection Input Connections PowerGas Solenoid Inlet Fitting InputRequirements for Maximum Output Code Requirements for Input ConnectionsRequirements for CSA Rated Output Requirements for Rated OutputSP-100 Table of Contents Wear eye, ear and body protec- tion OperationDesign Features Advantages Operational Features and ControlsGeneral Description OffWelding Operations Wire LoadingProcess Guidelines Sequence of OperationRefer to Figure B-4 Friction Brake AdjustmentsMaking a Weld Shielding GASOverload Protection SP-100 Accessories Section Replacement Parts 1ACCESSORIESLincoln GAS Regulator Kits K467 Input Line Cord Innershield Welding KitsMaintenance Section Maintenance Items Requiring no MaintenanceRoutine and Periodic Maintenance Changing the Contact TIP Changing Drive RollLiner trim length for the Magnum 100L gun red trigger Figure D.3 SP-100 SUB Assemblies SP-100 Theory of Operation Input Line VOLTAGE, FAN Motor and Main Transformer Figure E.1 Input Power CircuitsFigure E.2 Output Circuits Output CONTROL, RECTIFICA- Tion and Voltage Feedback3THEORY of Operation TRIGGER, GAS Solenoid and Wire DriveFigure E.4 SCR Operation SCR OperationThermostat protects the machine from Oscilloscope Waveforms Troubleshooting SectionHOW to USE Troubleshooting Guide 1TROUBLESHOOTING & RepairPC Board Troubleshooting Procedures Troubleshooting & RepairTroubleshooting Guide Authorized Field ServiceFacility Below Code 9794 only Possible Areas of Misadjustments Problems SymptomsRecommended Course of Action Code 9794 and AboveFeeding Problems Troubleshooting Guide Codes 9794 and above 6J1 10J2 1J1 1J2 Codes below SP-100 PC Board Connector LocationsScope Settings 9TROUBLESHOOTING & RepairVolts Volts/Div Normal Open Circuit Voltage WaveformTypical Output Voltage Waveform Machine Loaded VoltsAbnormal Open Circuit Voltage Waveform Procedure Procedure DescriptionFAN Blade and Motor Removal Tools RequiredMotor Removal Procedure Wire Drive Assembly Removal1A. for Codes Above 1B. for Codes belowRetest After Repair Wire Speed RangeMain Transformer Secondary Voltages Test Points Input Amps AT Rated Output Input Amps AC @ Output DCSP-100 Electrical Diagrams Section Wiring Diagrams WiringDiagram 4 5 1 M SP-100 Wiring Diagram Codes BelowElectrical Diagrams Control P.C. Board G1842 Electrical DiagramsControl P.C. Board G2314 SCR1, SCR2 SCR 81 Heatsink Asbly Control P.C. Board G2314Error Machine Schematic Codes 9794 and Above86R R63R64 1 5 K Machine Schematic Codes BelowSVM Error Reporting Form