Lincoln Electric SVM 122-A service manual Troubleshooting & Repair

Page 83

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F-39

F-39

TROUBLESHOOTING & REPAIR

ABNORMAL OPEN CIRCUIT VOLTAGE WAVEFORM

CONSTANT VOLTAGE SUBARC

ONE OUTPUT SCR NOT FUNCTIONING

CH1

0 volts

20 volts

5 ms

This is NOT the typical DC output voltage waveform. One output SCR is not functioning. Note the “gap” in the waveform. One SCR gate is dis- connected to simulate an open or non-functioning output SCR. Each vertical division represents 20 volts and each horizontal division repre- sents 5 milliseconds in time.

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

Image 83

Contents Idealarc TMDC-400 Safety Depends on YouCalifornia Proposition 65 Warnings SafetyElectric Shock can kill Cylinder may explode if damaged Précautions DE Sûreté Master Table of Contents for ALL Sections Table of Contents Installation Section Technical Specifications Idealarc DC-400 InstallationTilting Safety PrecautionsSelect Suitable Location LiftingElectric Shock can kill Input ConnectionsGround Connection Input Supply ConnectionsFigure A.3 Input Power Supply Connections Input Wire and Fuse SizeInput Supply Connection Diagram Reconnect ProcedureFigure A.6 Output Terminal Connections Output ConnectionsCycle Wire Feeder ConnectionsCycle 500 Amp 50% Duty Operation Section Operating Instructions Safety InstructionsOPERATIONB-2 General Description OperationFigure B.1 Case Front Controls Controls and SettingsOperation Operating Steps Remote ControlWelding Procedure Recommendations Welding OperationARC Striking with the NA-3 Start Board NA-3 Automatic Wire FeederLN-8 Semiautomatic Wire Feeder NA-5 Automative Wire FeederOverload Protection Auxiliary PowerTable of Contents Accessories Diode Option OPTIONS/ACCESSORIESFactory Installed Option Field Installed OptionsConnections Multiprocess Switch OperationAmptrol Adapter Cable K843 Remote Control Adapter Cable K864K843 Amptrol Adapter Installation Instructions Remote Output Control K857 with K864 Adapter Plug or K775Amptrol and Hi-Freq. Kit The Amptrol will start K843 Amptrol Adapter Installation InstructionsHI-FREQ KIT K799 for Codes 8634 and Above only Automatic Wire FeedersConnecting the NA-3 to the Idealarc DC-400 Terminal Strip Capacitor Discharge Circuit K828-1Connecting the NA-5 to the Idealarc DC-400 Terminal Strip To NA-3 or NA-5 Input Cable Plug K597-XX Input Cable Assembly Idealarc DC-400Connecting the LN-7 to the Idealarc DC-400 14-PIN Amphenol Semiautomatic Wire FeedersConnecting 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 Transformer Theory of OperationInput Line Voltage Contactor and MainOutput Mode and CONTROL, Rectification and Feedback Protective Devices and Circuits Figure E.4 SCR Operation SCR OperationTable of Contents Troubleshooting & Repair Section HOW to USE Troubleshooting Guide Troubleshooting & RepairPC Board can be damaged by static electricity PC Board Troubleshooting ProceduresOutput Problems Troubleshooting GuidePerform 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 Input Contactor Test Test ProcedureFigure F.2 Input Contactor Test Connections Test for Contact ContinuityControl Transformer T2 Voltage Test Figure F.3 Control Transformer and Lead Locations Control Transformer T2 Voltage TestTroubleshooting & Repair Main Transformer T1 Voltage Test Main Transformer T1 Voltage Test Figure F.6 Main Secondary Lead Test Points Troubleshooting & Repair Figure F.8 Control Board Plug P1 Location Plug P1 Phase Angle Winding VoltagesStatic SCR/DIODE Rectifier Bridge Test Figure F.9 Control Board and Snubber Board Plug Locations Static SCR/DIODE Rectifier Bridge TestSCR Test Active SCR Test P1 and P3 Locations Plug P5 Location Active SCR TestFigure F.15 Heat Sink Test Points Figure F.16 SCR Tester Circuit and SCR Connections CH1 Scope SettingsMaximum 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 Procedure FAN Motor and Blade Removal and ReplacementSCR/DIODE Rectifier Assembly Removal and Replacement Removal and Replacement SCR/DIODE Rectificer AssemblySCR Removal and Replacement Special Instructions SCR Removal and ReplacementFigure F.21 1/2 Wide Leaf Spring Procedure for the 1/2 Inch Wide SpringClamping Procedure For 1/4-20 CAP Screws Clamping Procedure For 1/4-28 CAP ScrewsInch Wide Spring Procedure forAfter 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 Removal of Lift Bail Main Transformer Removal & ReplacementFigure F.26 Choke Removal Removal of Choke and TOP Iron AssemblyFigure F.27 Epoxy MIX Application Areas Reassembly of Transformer CoilsFigure F.28 Coil Lead Placement Figure F.30 Primary Thermostat Location Reassemble the Lift Bail Reassembling the Main Transformer Into the MachineInput Idle Amps and Watts Input volts/Phase/Hertz Maximum Idle Amps Maximum Idle KWMode Input Hertz Open Circuit Volts Retest After RepairRetest After Repair Maximum Acceptable Output Voltage AT Minimum Ouput SettingsMode Control Settings Load Table of Contents Electrical Diagrams Section Idealarc DC400 LOW Voltage Wiring Diagram Codes 9847Only. It may not be accurate for all Wiring Diagram CodeControl DC400 Control PC Board G2588 LayoutTP2 Starting PC Board M14520 LayoutSnubber PC Board M15370 Layout 2586 Control PC Board G2588 SchematicGeneral Information Starting PC Board M14520 SchematicGeneral Information Snubber PC Board M15370 Schematic