Lincoln Electric SVM136-A Typical SCR Gate Voltage Waveform, Maximum Output Setting no Load

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F-30

F-30

TROUBLESHOOTING & REPAIR

TYPICAL SCR GATE VOLTAGE WAVEFORM

MAXIMUM OUTPUT SETTING – NO LOAD

	CH1
	0 volts
2 volts	5 ms

This is the typical SCR gate pulse voltage waveform. The machine was in an open circuit condition (no load) and operating properly. Note that each vertical division represents 2 volts and that each horizontal division represents 5 milliseconds in time.

Note: Scope probes connected at

SCR gate and cathode: (+) probe to gate, (-) probe to cathode.

SCOPE SETTINGS

Volts/Div	2V/Div.
Horizontal Sweep	5 ms/Div.
Coupling	DC
Trigger	Internal

IDEALARC CV-400

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Contents Idealarc CV-400 Safety California Proposition 65 WarningsElectric Shock can kill Cylinder may explode if damaged Précautions DE Sûreté Sûreté Pour Soudage a L’ArcMaster Table of Contents for ALL Sections Table of Contents Installation Section Installation Technical Specifications Idealarc CV-400Location and Ventilation Safety PrecautionsLifting Ground Connection Input Supply ConnectionsInput Wire and Fuse Size Return toReconnect Procedure Output Connections Connect Electrode and Work Leads to Output TerminalsFigure A.5 Output Terminal Connections Connect Wire Feeders Table of Contents Operation Section Operation Safety InstructionsOperating Instructions General Description Operational Features and ControlsDesign Features Recommended ProcessesWelding Capability LimitationsControls and Settings Figure B.1 Case Front ControlsWelding Operation Remote ControlLocal Control Auxiliary Power Overload ProtectionIdealarc CV-400 Table of Contents Accessories Factory Installed Options OPTIONS/ACCESSORIESField Installed Options Automatic Wire Feeders Connecting the NA-3 to the Idealarc CV-400Connecting the NA-5 to the Idealarc CV-400 FeederterminalAccessories Semiautomatic Wire Feeders Connecting the LN-7 to the Idealarc CV-400 Terminal StripConnecting the LN-8 or LN-9 to the Idealarc CV-400 Idealarc CV-400 Table of Contents Maintenance Safety Precautions Routine and Periodic Maintenance Return to Return to Section TOCFigure D.1 Idealarc CV-400 Table of Contents Theory of Operation Section Theory of Operation Input Line VOLTAGE, Contactor and Main TransformerOutput CONTROL, Rectification and Feedback Protective Devices Circuits Figure E.4 CV-400 Trigger and Thermal Light CircuitSCR Operation Figure E.5 SCR OperationIdealarc CV-400 Table of Contents Troubleshooting & Repair Section Troubleshooting & Repair HOW to USE Troubleshooting GuidePC Board Troubleshooting Procedures Electric Shock can killTroubleshooting Guide Output ProblemsOutput Problems SCR/Diode Perform the SCR/Diode Bridge SCR/Diode Rectifier Bridge Test Welding Problems Description Control Transformer T2 Voltage TestMaterials Needed Test Procedure Control Transformer T2 Voltage TestRight Side View Input Contactor Test Input Contactor Test Test for Contact Continuity Figure F.4 Input Contactor Test ConnectionsMain Transformer T1 Voltage Test Main Transformer T1 Voltage Test Figure F.6 Main Secondary Lead Test Points Blank Main Transformer T1 Voltage Test Static SCR/DIODE Rectifier Bridge Test Static SCR/DIODE Rectifier Bridge Test SCR Anode Remove ANY Insulating Paint Cathode SCR Active SCR Test Active SCR Test Figure F.15 Heat Sink Test Points Figure F.16 SCR Tester Circuit and SCR Connections Maximum Output Setting no Load Normal Open Circuit Voltage WaveformTypical Output Voltage Waveform Machine Loaded Maximum Output Setting no Load Typical SCR Gate Voltage WaveformAbnormal Output Voltage Waveform Machine Loaded ONE Output SCR not FunctioningInput Contactor CR1 CLEANING/REPLACEMENT DescriptionCleaning Procedure Contactor Replacement ProcedureFAN Motor and Blade Removal and Replacement FAN Motor and Blade Removal and Replacement ProcedureSCR/DIODE Rectifier Assembly Removal and Replacement SCR/DIODE Rectifier Assembly Removal and ReplacementSCR Removal and Replacement SCR Removal and Replacement Procedure 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 Mounting of Stud Type Diodes To Aluminum Heat SinksMain 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 BailOpen Circuit Voltages Retest After RepairInput Idle Amps and Watts Welding Output Load TestIdealarc CV-400 Electrical Diagrams Section GWiring Diagram Codes 10084, 10085 Wiring Diagram Code Control PC Board G2629-1 Layout Control PC Board G2629-1 Schematic Snubber Snubber PC Board M15370-3 Schematic Idealarc CV-400