Lincoln Electric SVM144-B service manual Static SCR Rectifier Assembly Test, Test Description

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F-19

TROUBLESHOOTING & REPAIR

F-19

STATIC SCR RECTIFIER ASSEMBLY TEST

WARNING

Service and repair should only be performed by Lincoln Electric factory trained personnel. Unauthorized repairs performed on this equipment may result in dan- ger to the technician or machine operator and will invalidate your factory war- ranty. For your safety and to avoid electrical shock, please observe all safety notes and precautions detailed throughout this manual.

If for any reason you do not understand the test procedures or are unable to per- form the test/repairs safely, contact the Lincoln Electric service department for technical troubleshooting assistance before you proceed. Call 1-888-935-3877.

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TEST DESCRIPTION

This test is used to quickly determine if an SCR or diode is shorted or “leaky.” See the Machine Waveform Section in this manual for normal and abnormal output waveforms.

MATERIALS NEEDED

Analog Volt-ohmmeter

POWER MIG 255 wiring diagrams (See Electrical Diagrams Section of this Manual) 3/8 in. Nutdriver

5/16 in. Nutdriver

1/2 in. Open end or socket wrench

POWER MIG 255

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Contents Power MIG Safety Electric Shock can kill Welding Sparks can cause fire or explosion SafetySûreté Pour Soudage a L’Arc Précautions DE SûretéMaster Table of Contents for ALL Sections Installation Section Table of ContentsTechnical Specifications Power MIG InstallationSafety Precautions Uncrating the Power MIGLocation Power MIG Figure A.2 Triple Voltage Machine Input Connections Shielding GAS GUN and Cable InstallationSection B Operation SectionFumes and Gases can be dangerous OPERATIONB-2Product Description OperationWelding Capability LimitationsDescription of Controls Wire Reel Loading READI-REELS, SPOOLS, or Coils Procedure for Changing Drive and Idle Roll SetsSetting RUN-IN Speed on STAN- Dard Power MIG Feeder Feeding Wire ElectrodeIdle Roll Pressure Setting To Start the WelderMaking a Weld Avoiding Wire Feeding ProblemsInput Line Voltage Protection FAN ControlSection C Accessories SectionDrive Roll Kits AccessoriesK363P READI-REEL Adapter Dual Cylinder Mounting KIT K1702-1Operating Instructions For Timer KIT Spool GUN Adapter KIT Making a Weld with the Spool GUN, Spool GUN InstalledSection D Maintenance SectionMaintenance Routine and Periodic MaintenanceGUN Tubes and Nozzles Figure D.1 Component Locations Liner Removal Replacement Contact TIP and GAS Nozzle InstallationTo open up the handle 5MAINTENANCED-5Description English Size Metric Size Table D.2Section E Theory of Operation SectionTheory of Operation Input Line VoltageMain Transformer Feedback Control Output RectificationFigure E.4 Constant Voltage Output Constant Voltage OutputFeedback Wire Drive MotorWire Feed Overload Protection Thermal and Overload ProtectionOvercurrent Protection Figure E.6 SCR Operation SCR OperationPower MIG Section F Troubleshooting & Repair SectionHOW to USE Troubleshooting Guide Troubleshooting & RepairWorkstations PC Board Troubleshooting ProceduresOutput Problems SCR Rectifier Rectifier Function Problems Wire Feeding Problems Welding Problems Welding Problems Test Description Main Transformer TestMain Transformer Test Test ProcedureFigure F.1 Troubleshooting and Repair Rectifier Diode Bridge Test Test DescriptionMaterials Needed Rectifier Diode Bridge Testing 208R 206 28 VAC 209R Power MIG Static SCR Rectifier Assembly Test Static SCR Rectifier Assembly Test Active SCR Rectifier Assembly Test Power MIG Active SCR Rectifier Assembly Test Active SCR Rectifier Assembly Test Figure F.7 Location Leads X2 Open switch SW-1 Wire Drive Motor and Tachometer Feedback Test Wire Drive Motor and Tachometer Feedback Test 515B 206B 15 VDC 5J1 1J1 Test for Supply Voltage to Tachometer555 206B To 3.5 VDC 6J1 1J1 Test for Feedback Voltage to Control BoardVolts Normal Open Circuit Voltage WaveformTypical Output Voltage Waveform Machine Loaded Machine Loaded to 250 Amps AT 26 VDC Scope SettingsMachine Loaded to 220 Amps AT 22 VDC Scope Settings Troubleshooting & Repair Typical SCR Gate Voltage Waveform Power MIG Description Control PC Board Removal and Replacement ProcedureControl PC Board Removal and Replacement ProcedureFigure F.11 Control Board Mounting Power MIG Wire Drive Assembly Removal and Replacement Procedure 41TROUBLESHOOTING & REPAIRF-41Procedure Wire Drive Assembly Removal and ReplacementTOC Power MIG SCR Output Rectifier Removal and Replacement Procedure SCR Output Rectifier Removal and Replacement Figure F.15 Right Heat Sink Lead Disconnection Power MIG Capacitor Bank Removal and Replacement Procedure Capacitor Bank Removal and Replacement Troubleshooting & Repair Main Transformer and Output Choke Removal and ReplacementTOC Power MIG FAN Motor Assembly Removal and Replacement Procedure FAN Motor Assembly Removal and Replacement Wire Speed Range Troubleshooting and RepairRetest After Repair Open Circuit VoltagePower MIG Electrical Diagrams Section Wiring Diagram Entire Machine Code 10563 L10979 Power MIG 255 208/230VWiring Diagram Entire Machine Code 10583 L10980 Power MIG 255 230/460/575VWiring Diagram Entire Machine Code 10986 L11980 Power MIG 255 230/460/575Wiring Diagram Entire Machine Code 10990 L11979 Power MIG 255 208/230Control PC Board Schematic G3520-1D1 3521 Control PC Board Assembly G3521-1Powermig Display PC Board Schematic L10951Lincoln Electric CO Display PC Board Assembly L10952-124374 S Snubber PC Board Schematic S2437400 ~.04 Snubber PC Board Assembly M19248-1SVM Error Reporting Form