Lincoln Electric SVM 119-A service manual Figure F.4 SCR 1 Test Points

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F-15	TROUBLESHOOTING & REPAIR	F-15
	TROUBLESHOOTING & REPAIR

STATIC SCR RECTIFIER ASSEMBLY TEST (CONTINUED)

NOTE: DO NOT DISASSEMBLE THE

SCR RECTIFIER HEAT SINK ASSEM-

BLY.

6.Test for high or infinite resistance from the anode to the cathode of SCR 1. See Figure F.4. Use an analog ohmmeter (Multimeter).

FIGURE F.4 - SCR 1 Test Points.

7.Test for high or infinite resistance from the cathode to the anode of SCR 1 by reversing the meter leads. See Figure F.4.

a.If a high or infinite resistance is indicated for both tests 6 and 7, the SCR 1 is not “shorted”.

b.If a low resistance is indicated in either tests 6 or 7, the SCR is faulty. Replace SCR Assembly.

8.Repeat Steps #7 to test SCR 2.

9.Reconnect leads X2 and X3.

10.Reconnect Plugs J3 and J6.

11.If this test did not identify the prob- lem or to further test the SCR, go to the Active SCR Test.

WIRE-MATIC 255

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Contents WIRE-MATIC Safety Depends on YouARC Rays can burn SafetyElectric Shock can kill 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 Input Connections Safety PrecautionsSelect Proper Location 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 K585-1K468 8 Spool Adapter Drive Roll Kits64 1.2mm Aluminum Feeding KIT K673-1 K363P READI-REEL AdapterDual Cylinder Mounting KIT K671-1 Maintenance Table of Contents Maintenance SectionRoutine and Periodic Maintenance Perform the following dailyMaintenance Drive Rolls and Guide Tubes Cable CleaningContact TIP and GAS Nozzle Installation 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 Input Volts/Hertz Wire Speed RangeOpen Circuit Voltage 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