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Lincoln Electric SVM 119-A service manual Thermal Protection

Models: SVM 119-A

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E-5	THEORY OF OPERATION	E-5
	THEORY OF OPERATION

THERMAL PROTECTION

THERMAL PROTECTION

A thermostat protects the machine from excessive operating temperatures. Excessive operating temper- atures may be caused by a lack of cooling air or oper- ating the machine beyond the duty cycle and output rating. There are three thermostats within the WIRE- MATIC 255 machine. One of the thermostats, located on the output choke, energizes the cooling fan motors when required. The other choke thermostat "opens" the trigger circuit, preventing machine weld output and wire feed, if excessive operating temperatures are detected. The third thermostat insures that the fan motors are operating when required.

The thermostats are self-resetting once the machine cools sufficiently. If the thermostat shutdown is caused by excessive output or duty cycle and the fans are operating normally, the power switch may be left on and the reset should occur within a 15 minute period. If the fans are not turning or the air intake louvers are obstructed, then the input power must be removed and the fan problem or air obstruction be corrected.

NOTE: Unshaded areas of Block Logic

Diagram are the subject of discussion

WIRE-MATIC 255

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Lincoln Electric SVM 119-A service manual Thermal Protection

Contents

WIRE-MATIC Safety Depends on YouSafety Electric Shock can killARC Rays can burn Fumes and Gases can be dangerousCylinder may explode if damaged Welding Sparks can cause fire or explosionElectric and MAG- Netic Fields May be dangerousIii Précautions DE Sûreté Sûreté Pour Soudage a L’ArcWIRE-MATIC Table of Contents Table of Contents Installation Table of Contents Installation SectionTechnical Specifications Wire-Matic-255 Safety Precautions Select Proper LocationInput Connections StackingFuse and Wire Sizes Connect Shielding GAS Reconnect Procedure Figure A.4 Input Gas Supply ConnectionsFigure A.5 Reconnect Diagram For 208/230/1/60 Machines Connect Output Components ConnectionsWire Size Conversion Parts GUN and Cable InstallationWIRE-MATIC Table of Contents Operation Section OperationSafety Instructions General DescriptionWELDING, Cutting Design Features Advantages Recommended Processes and EquipmentMachine Capability LimitationsDuty Cycle Amps Volts Controls and Settings Figure B.1 Operator ControlsUsing the Wire Drive Roll Figure B.2 Wire Reel LoadingFeeding Electrode Setting Idle Roll Pressure Operating StepsMaking a Weld WIRE-MATIC Accessories Table of Contents Accessories SectionOPTIONS/ACCESSORIES Magnum GUN Connection KIT Optional K466-6K672-1 Spool GUN Adapter KIT Making a Weld with the Spool GUN Adapter K672-1 Installed Timer KIT K585-1 Timer KIT Installation Optional K585-1Drive Roll Kits 64 1.2mm Aluminum Feeding KIT K673-1K468 8 Spool Adapter K363P READI-REEL AdapterDual Cylinder Mounting KIT K671-1 Maintenance Table of Contents Maintenance SectionRoutine and Periodic Maintenance Perform the following dailyMaintenance Cable Cleaning Contact TIP and GAS Nozzle InstallationDrive Rolls and Guide Tubes GUN Tubes and NozzlesLiner Removal Replacement Figure D.2 Liner maintenanceGUN Handle Disassembly To open up the handleDescription English Size Metric Size WIRE-MATIC Table of Contents Theory of Operation Section Theory of OperationInput Line Voltage and Main TransformerOutput Rectification Feedback ControlConstant Voltage Output Figure E.4 Constant Voltage OutputWire Drive Motor FeedbackThermal Protection SCR Operation Figure E.6 SCR OperationWIRE-MATIC Troubleshooting & Repair Table of Contents Troubleshooting & Repair SectionHOW to USE Troubleshooting Guide Recommended Course of ActionPC Board Troubleshooting Procedures Electric Shock can killBoard can be dam- aged by static electricity Main Transformer Rectifier Assembly Test To Section TOC SCR Rectifier Perform the Wire Drive Motor Liquid elec Trolyte in these capacitors isPerform the Output Rectifier Main Transformer Test Test DescriptionMaterials Needed Main Transformer Test Test Procedure ON/OFF Power Switch will be hot during these testsLead Plug Location Static SCR Rectifier Assembly Test Leads Figure F.4 SCR 1 Test Points Active SCR Rectifier Assembly Test Leads Figure F.7 SCR Tester Circuit SCR connectionsWire Drive Motor and Tachometer Feedback Test Wire Drive Motor and Tachometer Feedback Test Test Procedure Test for Supply Voltage to Tachometer Test for Feedback Voltage to the Control BoardScope Settings Normal Open Circuit Voltage WaveformMachine Loaded to 250 Amps AT 26 VDC Scope Settings Typical Output Voltage Waveform Machine LoadedMachine Loaded to 220 Amps AT 22 VDC Scope Settings Troubleshooting & Repair Typical SCR Gate Voltage Waveform Control PC Board Removal and Replacement Removal and Replacement ProcedureRemoval and REPLACE- Ment Procedure Wire Drive Assembly Removal and Replacement Procedure Figure F.11 Wire Drive Assembly RemovalSCR Output Rectifier Removal & Replacement Right side heat sink See Figure F.14 Disconnection Heat Sink LeadCapacitor Bank Removal and Replacement Bank Removal Replacement ComponentsMain Transformer Removal and Replacement Power Switch FAN Motor and FAN Removal and Replacement FAN Motor and FAN Removal and Replacement Procedure Figure F.16 Fan Motor and Fan Removal ComponentsTroubleshooting & Repair Wire Speed Range Open Circuit VoltageInput Volts/Hertz 230/60 375WIRE-MATIC Table of Contents Electrical Diagrams Section WIRE-MATIC Electrical Diagrams Wiring Diagram 208/230 CodeWire Matic 255 230 / 460 Wiring Diagram 230/460/575 CodeControl PC Board G2803 Schematic Wirematic 255 Control Control PC Board G2803 Layout