Manuals / Lincoln Electric / Power Tools / Welder

Lincoln Electric SVM141-A service manual Machine Loaded to 275 Amps, AT 31 VDC

Models: SVM141-A

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F-38

F-38

TROUBLESHOOTING & REPAIR

TYPICAL OUTPUT VOLTAGE WAVEFORM - MACHINE LOADED

DC TIG MODE

CAUTION

HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.

•Perform all voltage and waveform checks with high frequency circuit OFF.

•Perform High Frequency Disable Procedure.

0 V

20 V

2 ms

MACHINE LOADED TO 275 AMPS

AT 31 VDC.

This is the typical DC (+) output volt- age waveform generated from a prop- erly operating machine. Note that each vertical division represents 20 volts and that each horizontal division represents 2 milliseconds in time. The machine was loaded with a resistance grid bank.

NOTE: Scope probes connected at

machine output terminals: (+) probe to electrode, (–) probe to work.

SCOPE SETTINGS

Volts/Div	20 V/Div.
Horizontal Sweep	2 ms/Div.
Coupling	DC
Trigger	Internal

SQUARE WAVE TIG 275

Image 78

Lincoln Electric SVM141-A service manual Machine Loaded to 275 Amps, AT 31 VDC

Contents

Safety Depends on You Square Wave TIGSafety Square Wave TIGElectric Shock can kill ARC Rays can burnFumes and Gases can be dangerous Cylinder may explode if damaged IiiPrécautions DE Sûreté Sûreté Pour Soudage a L’ArcMaster Table of Contents for ALL Sections Table of Contents Installation Section Installation Technical Specifications Square Wave TIGSafety Precautions Input Supply Connections Figure A.1Input Reconnect Procedure Return to Section TOC To Section TOCWork Cable Connection User Supplied ConnectorsOutput Connections Table A.1TIG Torch Connection Cylinder could explode if damagedTWIST-MATE Adapter for LA-9 and LA-17 TIG Torch TWIST-MATE Adapter for LW-18 and LW-20 TIG TorchCompleted Assembly Square Wave TIG Table of Contents Operation Section Fumes and Gases can be dangerous OperationElectric Shock can kill Welding Sparks can cause fire or explosionDesign Features Advantages General DescriptionRecommended Processes and Equipment Welding Capability LimitationsControls and Settings Figure B.1 Control PanelTIG Welding Guidelines Welding OperationTIG Welding Twist Mate ElectrodeTIG Welding Sequence of Operation 2-Step TIG Mode Table B.2 Recommended Polarity Settings for TIG WeldingTIG Welding Sequence of Operation 4-Step TIG Mode Advanced TIG Welding Features Hand and Foot Amptrol OperationAC Wave Balance and Auto Balance Hertz Domestic Machines Auxiliary PowerStick Welding 50/60 Hertz European MachinesSquare Wave TIG Table of Contents Accessories Section C-1Section C-1Accessories Included with Machine Optional AccessoriesK963-1, -2 Hand Amptrol Table of Contents Maintenance Section Maintenance Routine and Periodic MaintenanceOverload Protection Control PC Board Component Location and AccessSpark GAP ASSEMBLY, High Voltage Transformer Display PC BOARD, ARC STARTER/BYPASS PC BoardFigure D.2 Major Component Locations Table of Contents Theory of Operation Section Input Power Circuit Theory of OperationOutput Rectification Control Board and Feedback Figure E.3 Output RECTIFICATION, Control Board and FeedbackHigh Voltage / High Frequency Circuit Figure E.4 High Voltage / High Frequency CircuitDC Welding Output Figure E.5 DC Welding OutputAC Welding Output Figure E.7 AC Welding OutputSCR Operation Figure E.9 SCR OperationProtective Circuits Thermal ProtectionOverload Protection Table of Contents Troubleshooting & Repair Section Disable Procedure Troubleshooting & RepairHOW to USE Troubleshooting Guide High Voltage / High Frequency can damage test equipmentPC Board Troubleshooting Procedures PC Board can be damaged by static electricityTroubleshooting Guide Observe Safety GuidelinesDetailed in the beginning of this manual Perform the SCR Bridge Test Troubleshooting & Repair Connections Troubleshooting Guide Troubleshooting & Repair TIG Welding Problems Electric Shock Can KillTroubleshooting & Repair To Technical Specifications Stick Welding Problems Function Problems 15F-15Function Problems Installation Troubleshooting & Repair High Frequency Circuit Disable Procedure Test DescriptionMaterials Needed High Frequency Circuit Disable Procedure ProcedureT1 Main Transformer Test Test Procedure T1 Main Transformer TestReplace the case side covers Test Points Primary WINDINGS1GAS Water Solenoid Test GAS Water Solenoid Test Figure F.3 GAS Solenoid LocationStatic SCR Test Static SCR Test Figure F.4 Plug J1 Location on Control BoardAssembly Removal and Replacement Active SCR Test DescriptionActive SCR Test Figure F.6 Plug J1 Location on Control BoardFigure F.7 Active SCR Test Setup SCR Bridge Assembly Removal and Replacement AC TIG Mode Scope SettingsNormal Open Circuit Voltage Waveform DC TIG Mode AC Stick Mode DC Stick Mode Typical Output Voltage Waveform Machine Loaded Machine Loaded to 255 AmpsAT 30 VAC Machine Loaded to 275 Amps AT 31 VDCAC Stick Mode DC Stick Mode 50 V/Div High Voltage Transformer Removal Replacement Replacement Removal ProcedureHigh Voltage Transformer Removal Replacement Procedure Figure F.10 High Voltage Transformer Mounting InsulatorsSCR Bridge Assembly Removal and Replacement SCR Bridge Assembly Removal and Replacement Using the 3/8 nut driver, remove the caseFigure F.13 SCR Bridge Connections Refer to Figures F.11 F.13 Polarity Switch Removal and Replacement Polarity Switch Removal and Replacement Allen Screw Control Knobs Polarity Switch HandlePOS Micro Switch Leads Square Wave TIG 253Figure F.16 Polarity Switch Wiring Diagram Replacement Procedure For Steps 9--17, see Figure F.15 and F.16Description Main Transformer and Output Choke Assembly Removal and ReplacementFigure F.18 Transformer Connections Figure F.19 Polarity Switch Connections Choke NEG POS Micro Switch LeadsReassembly Procedure Refer to Figures F.17 F.19Input Idle Amps Minimum Acceptable Output Voltage AT Maximum Output SettingRetest After Repair Open Circuit VoltagesSquare Wave TIG Section G Electrical WiringDiagram L10747 TIGDiagram L10747-2 SquarewaveElectrical Diagrams Control Board Schematic G3358-1Control Board Schematic G3358-2 OCI4 TRI3 MT2Display Board Schematic L10768 Return to Section Return to Section TOC To Section TOCBypass Display Board Layout L10770-1 L10770-17-24-98XXX Bypass Board Layout L10121-1 10G-10Square Wave TIG