Lincoln Electric SVM136-A service manual Figure F.16 SCR Tester Circuit and SCR Connections

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F-27

F-27

TROUBLESHOOTING & REPAIR

ACTIVE SCR TEST (continued)

FIGURE F.16 – SCR TESTER CIRCUIT AND SCR CONNECTIONS

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9.Construct the circuit shown in Figure F.16. One 6-volt lantern battery can be used., Set voltmeter scale low, at approximately 0-5 volts or 0-10 volts.

10.Test the voltage level of the battery. Short leads (A) and (C). Close switch SW-1. Battery voltage should be 4.5 volts or higher. If lower, replace the battery.

11.Connect the tester to the SCR 1 as shown in Figure F.16.

a.Connect tester lead (A) to the anode.

b.Connect tester lead (C) to the cathode.

c.Connect tester lead (G) to the gate.

12.Close switch SW-1.

NOTE: Switch SW-2 should be open.

13.Read meter for zero voltage.

a.If the voltage reading is higher than zero, the SCR is shorted.

14.Close or keep closed switch SW-1.

15.Close switch SW-2 for 2 seconds. Release and read meter.

a.If the voltage is 3-6 volts while the switch is closed and after the switch is open, the SCR is functioning.

b.If the voltage is 3-6 volts only when the switch is closed or if there is no voltage when the switch is closed, the SCR is defective.

NOTE: Be sure the battery is function- ing properly. A low battery can affect the results of the test. Repeat Battery Test Procedure in Step 10 if needed.

16.Open switch SW-1.

17.Reconnect the tester leads. See Figure F.16.

a.Connect tester lead (A) to the cathode.

b.Connect tester lead (C) to the anode.

c.Disconnect test lead (G) from the gate.

18.Close switch SW-1.

19.Read meter for zero voltage.

a.If the voltage is zero, the SCR is func- tioning.

b.If the voltage is higher than zero, the SCR is shorted.

20.Perform the Active Test Procedure outlined in Steps 11-19 for SCRs 2 and 3.

21.Replace all SCR assemblies that do not pass the above tests.

22.Replace all molex plugs onto the control board and snubber board. Reconnect posi- tive capacitor lead and small lead terminal.

23.Reconnect lead #204 to resistor R2.

IDEALARC CV-400

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Contents Idealarc CV-400 California Proposition 65 Warnings SafetyElectric Shock can kill Cylinder may explode if damaged Sûreté Pour Soudage a L’Arc Précautions DE SûretéMaster Table of Contents for ALL Sections Table of Contents Installation Section Technical Specifications Idealarc CV-400 InstallationLocation and Ventilation Safety PrecautionsLifting Input Supply Connections Ground ConnectionReturn to Input Wire and Fuse SizeConnect Electrode and Work Leads to Output Terminals Reconnect Procedure Output ConnectionsFigure A.5 Output Terminal Connections Connect Wire Feeders Table of Contents Operation Section Operation Safety InstructionsOperating Instructions Recommended Processes Operational Features and ControlsDesign Features General DescriptionLimitations Welding CapabilityFigure B.1 Case Front Controls Controls and SettingsWelding Operation Remote ControlLocal Control Overload Protection Auxiliary PowerIdealarc CV-400 Table of Contents Accessories Factory Installed Options OPTIONS/ACCESSORIESField Installed Options Connecting the NA-3 to the Idealarc CV-400 Automatic Wire FeedersFeederterminal Connecting the NA-5 to the Idealarc CV-400Accessories Connecting the LN-7 to the Idealarc CV-400 Terminal Strip Semiautomatic Wire FeedersConnecting the LN-8 or LN-9 to the Idealarc CV-400 Idealarc CV-400 Table of Contents Maintenance Return to Return to Section TOC Safety Precautions Routine and Periodic MaintenanceFigure D.1 Idealarc CV-400 Table of Contents Theory of Operation Section Input Line VOLTAGE, Contactor and Main Transformer Theory of OperationOutput CONTROL, Rectification and Feedback Figure E.4 CV-400 Trigger and Thermal Light Circuit Protective Devices CircuitsFigure E.5 SCR Operation SCR OperationIdealarc CV-400 Table of Contents Troubleshooting & Repair Section HOW to USE Troubleshooting Guide Troubleshooting & RepairElectric Shock can kill PC Board Troubleshooting ProceduresOutput Problems Troubleshooting GuideOutput Problems SCR/Diode Perform the SCR/Diode Bridge SCR/Diode Rectifier Bridge Test Welding Problems Description Control Transformer T2 Voltage TestMaterials Needed Control Transformer T2 Voltage Test Test ProcedureRight Side View Input Contactor Test Input Contactor Test Figure F.4 Input Contactor Test Connections Test for Contact ContinuityMain 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 Normal Open Circuit Voltage Waveform Maximum Output Setting no LoadTypical Output Voltage Waveform Machine Loaded Typical SCR Gate Voltage Waveform Maximum Output Setting no LoadONE Output SCR not Functioning Abnormal Output Voltage Waveform Machine LoadedDescription Input Contactor CR1 CLEANING/REPLACEMENTContactor Replacement Procedure Cleaning ProcedureFAN 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 Rectifier AssemblySCR Removal and Replacement SCR Removal and Replacement Figure 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 To Aluminum Heat Sinks Mounting of Stud Type DiodesMain 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 MachineWelding Output Load Test Retest After RepairInput Idle Amps and Watts Open Circuit VoltagesIdealarc CV-400 Section G Electrical DiagramsWiring 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