Lincoln Electric SVM136-A service manual SCR Removal and Replacement

Page 79

Return to Section TOC

Return to Master TOC

F-39

F-39

TROUBLESHOOTING & REPAIR

SCR REMOVAL AND REPLACEMENT (continued)

FIGURE F.20 – SCR DETAILS

Return to Section TOC

Return to Section TOC

Return to Master TOC

Return to Master TOC

SPECIAL INSTRUCTIONS

NOTE: Before disassembling the existing recti- fier, note toward which heat sink the outer metal ring of the power SCR is mounted. Also, note the positioning of the gate lead of the SCR. Failure to reinstall the new SCR in the same ori- entation as the original may result in subsequent damage to the new SCR and other components of the welder. See Figure F.20.

CAUTION

The unclamping and clamping procedure out- lined below is critical for the prevention of inter- nal SCR damage. Failure to follow this proce- dure may result in subsequent damage of the SCR. Handle all SCRs with care.

5.Clean the area on the heat sink around the SCR mounting surface, using a putty knife or similar tool. DO NOT SCRATCH THE SCR MOUNTING SURFACE.

6.Polish each heat sink’s mounting surface using NO. 000 fine steel wool. Wipe surface clean with a lint-free cloth or paper towel.

7.Inspect the mounting surfaces of each new SCR.

a.Remove all burrs and wipe clean. Do not use steel wool or any abrasive cleanser on the SCR mounting surfaces.

8.Apply a thin (0.001” to 0.003”) layer of PEN- ETROX A-13 (Lincoln Electric #E2529) or PENETROX A, heat sink compound, to each heat sink’s SCR mounting surface.

PROCEDURE

a. Care must be used to prevent foreign

 

material contamination of the SCR to

 

heat sink junction.

Return to Section TOC

Return to Master TOC

1.Remove the main input supply power to the machine.

2.Perform the SCR/Diode Rectifier Assembly Removal and Replacement pro- cedure.

3.Alternately loosen nuts 1/2 turn each until heat sinks are loose. Remove nuts and leaf spring. IT IS RECOMMENDED THAT NEW HARDWARE, LEAF SPRING AND HOUSING BE USED FOR REASSEMBLY.

4.Remove the old SCR.

9.Place the new SCR between the heat sinks. Be sure that the outer metal ring of the SCR is facing toward the same heat sink as the old SCR’s metal ring. Be sure that the roll pin of the heat sink engages the “hole” in the SCR. The SCR contact surfaces must sit flat against both heat sink surfaces.

IDEALARC CV-400

Page 78 Page 80
Image 79
Page 78 Page 80
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
Top Page Image Contents