Lincoln Electric SVM 122-A service manual Troubleshooting & Repair

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F-36

F-36

TROUBLESHOOTING & REPAIR

TYPICAL OUTPUT VOLTAGE WAVEFORM – MACHINE LOADED

CONSTANT VOLTAGE FCAW/GMAW MODE

CH1

0 volts

20 volts

5 ms

This is the typical DC open circuit voltage waveform generated from a properly operating machine. Note that each vertical division represents 20 volts and that each horizontal divi- sion represents 5 milliseconds in time. The machine was loaded with a resistance grid bank. The DC-400 meters read 400 amps at 36 VDC.

Note: Scope probes connected at

machine output terminals: (+) probe to positive terminal, (-) probe to neg- ative terminal.

SCOPE SETTINGS

Volts/Div	20V/Div.
Horizontal Sweep	5 ms/Div.
Coupling	DC
Trigger	Internal

IDEALARC DC-400

LINCOLN ®

ELECTRIC

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Contents Safety Depends on You Idealarc TMDC-400Safety California Proposition 65 WarningsElectric Shock can kill Cylinder may explode if damaged Précautions DE Sûreté Master Table of Contents for ALL Sections Table of Contents Installation Section Installation Technical Specifications Idealarc DC-400Safety Precautions Select Suitable LocationLifting TiltingInput Connections Ground ConnectionInput Supply Connections Electric Shock can killInput Wire and Fuse Size Figure A.3 Input Power Supply ConnectionsReconnect Procedure Input Supply Connection DiagramOutput Connections Figure A.6 Output Terminal ConnectionsCycle Wire Feeder ConnectionsCycle 500 Amp 50% Duty Operation Section Operating Instructions Safety InstructionsOPERATIONB-2 Operation General DescriptionControls and Settings Figure B.1 Case Front ControlsOperation Remote Control Welding Procedure RecommendationsWelding Operation Operating StepsNA-3 Automatic Wire Feeder ARC Striking with the NA-3 Start BoardNA-5 Automative Wire Feeder LN-8 Semiautomatic Wire FeederAuxiliary Power Overload ProtectionTable of Contents Accessories OPTIONS/ACCESSORIES Factory Installed OptionField Installed Options Diode OptionMultiprocess Switch Operation ConnectionsRemote Control Adapter Cable K864 K843 Amptrol Adapter Installation InstructionsRemote Output Control K857 with K864 Adapter Plug or K775 Amptrol Adapter Cable K843K843 Amptrol Adapter Installation Instructions Amptrol and Hi-Freq. Kit The Amptrol will startAutomatic Wire Feeders Connecting the NA-3 to the Idealarc DC-400 Terminal StripCapacitor Discharge Circuit K828-1 HI-FREQ KIT K799 for Codes 8634 and Above onlyConnecting the NA-5 to the Idealarc DC-400 Terminal Strip Cable Plug K597-XX Input Cable Assembly Idealarc DC-400 To NA-3 or NA-5 InputSemiautomatic Wire Feeders Connecting the LN-7 to the Idealarc DC-400 14-PIN AmphenolConnecting the LN-7 to the Idealarc DC-400 Terminal Strip Accessories Accessories Figure C.11 Idealarc DC-400/LN-742 Connection Diagram Table of Contents Maintenance Routine and Periodic Maintenance Figure D.1 General Component Locations Table of Contents Theory of Operation Section Theory of Operation Input Line VoltageContactor and Main TransformerOutput Mode and CONTROL, Rectification and Feedback Protective Devices and Circuits SCR Operation Figure E.4 SCR OperationTable of Contents Troubleshooting & Repair Section Troubleshooting & Repair HOW to USE Troubleshooting GuidePC Board Troubleshooting Procedures PC Board can be damaged by static electricityTroubleshooting Guide Output ProblemsPerform the Main Transformer Rectifier Bridge Test Tifier Bridge Test Output Problems Test Perform the SCR/Diode Rec Tifier Bridge Test Function Problems Form the SCR/Diode Rectifier Welding Problems Toxic. Avoid contact with any Portion of your body. CleanTrolyte in these capacitors is Make sure welding process is Materials Needed Input Contactor TestDescription Test Procedure Input Contactor TestTest for Contact Continuity Figure F.2 Input Contactor Test ConnectionsControl Transformer T2 Voltage Test Control Transformer T2 Voltage Test Figure F.3 Control Transformer and Lead LocationsTroubleshooting & Repair Main Transformer T1 Voltage Test Main Transformer T1 Voltage Test Figure F.6 Main Secondary Lead Test Points Troubleshooting & Repair Plug P1 Phase Angle Winding Voltages Figure F.8 Control Board Plug P1 LocationStatic SCR/DIODE Rectifier Bridge Test Static SCR/DIODE Rectifier Bridge Test Figure F.9 Control Board and Snubber Board Plug LocationsSCR Test Active SCR Test Active SCR Test P1 and P3 Locations Plug P5 LocationFigure F.15 Heat Sink Test Points Figure F.16 SCR Tester Circuit and SCR Connections Scope Settings CH1Maximum Output Setting no Load Troubleshooting & Repair Troubleshooting & Repair Troubleshooting & Repair 2V/Div Troubleshooting & Repair Input Contactor CR1 CLEANING/REPLACEMENT Contactor Replacement Procedure Input Contactor CR1 CLEANING/REPLACEMENTCleaning Procedure FAN Motor and Blade Removal and Replacement FAN Motor and Blade Removal and Replacement ProcedureSCR/DIODE Rectifier Assembly Removal and Replacement SCR/DIODE Rectificer Assembly Removal and ReplacementSCR Removal and Replacement SCR Removal and Replacement Special InstructionsProcedure for the 1/2 Inch Wide Spring Figure F.21 1/2 Wide Leaf SpringClamping Procedure For 1/4-28 CAP Screws Clamping Procedure For 1/4-20 CAP ScrewsProcedure for Inch Wide SpringAfter Replacing the SCRs Mounting of Stud Type Diodes to Aluminum Heat Sinks Diode Stud Foot Inch Size Pounds Mounting of Stud Type Diodes to AluminumHeat Sinks Main Transformer Removal and Replacement Main Transformer Removal & Replacement Removal of Lift BailRemoval of Choke and TOP Iron Assembly Figure F.26 Choke RemovalReassembly of Transformer Coils Figure F.27 Epoxy MIX Application AreasFigure F.28 Coil Lead Placement Figure F.30 Primary Thermostat Location Reassembling the Main Transformer Into the Machine Reassemble the Lift BailInput volts/Phase/Hertz Maximum Idle Amps Maximum Idle KW Mode Input Hertz Open Circuit VoltsRetest After Repair Input Idle Amps and WattsRetest After Repair Maximum Acceptable Output Voltage AT Minimum Ouput SettingsMode Control Settings Load Table of Contents Electrical Diagrams Section Idealarc DC400 Wiring Diagram Codes 9847 LOW VoltageWiring Diagram Code Only. It may not be accurate for allControl PC Board G2588 Layout Control DC400Starting PC Board M14520 Layout TP2Snubber PC Board M15370 Layout Control PC Board G2588 Schematic 2586Starting PC Board M14520 Schematic General InformationSnubber PC Board M15370 Schematic General Information