Lincoln Electric R3R-500, R3R-300 service manual SCR Test

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F-27

F-27

TROUBLESHOOTING & REPAIR

STATIC SCR/DIODE RECTIFIER BRIDGE TEST (continued)

FIGURE F.15 – HEAT SINK AND SCR TEST POINTS

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REMOVE INSULATING PAINT

CATHODE

ANODE

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7.Remove the red insulating paint from the heat sink test points. See Figure F.15.

NOTE: Do not disassemble the heat sink.

8.Measure the resistance from the anode to the cathode of SCR 1 using an analog volt/ohmmeter (multimeter) set at R x 1000 scale. See Figure F.15.

a.Reverse the meter leads and measure the resistance from the cathode to the anode of SCR 1. See Figure F.15.

b.If a low resistance is measured in either meter polarity, SCR1 is faulty. Replace SCR 1.

9.Test the resistance of SCR 2 and SCR 3 using the same procedure described in Step 8.

10.Measure the resistance of diode D1 from anode (+probe) to cathode (-probe) using an analog ohmmeter set at R x 1000 scale. The resistance should be low. See Figure F.15.

a.Reverse the meter leads and measure the resistance from cathode (+probe) to anode (-probe) of diode D1. The resistance should be high. See Figure F.15.

b.If a low resistance is measured in both meter polarities, diode D1 is shorted. Replace diode D1.

c.If a high resistance is measured in both meter polarities, diode D1 is open. Replace diode D1.

11.Test diodes D2, D3 and D4 for proper oper- ation using the same procedure described in Step 10.

12.Reconnect all leads and molex plugs. Resolder lead #204 at resistor R3.

13.If this test did not identify the problem or to further test the SCRs, go to the Active

SCR Test.

IDEALARC R3R

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Contents Idealarc R3R-300, -400 California 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 R3R-300 InstallationTechnical Specifications Idealarc R3R-400 Technical Specifications Idealarc R3R-500 Select Suitable Location Safety PrecautionsLifting TiltingGround Connection Input ConnectionsInput Supply Connections Figure A.2 Input Power Supply Connections Input Wire and Fuse SizeInput Supply Connection Diagram Reconnect ProcedureReturn to Section Output Connections STICK, TIG, AIR/CARBON ARC CuttingIdealarc R3R Table of Contents Operation Section OPERATIONB-2 Safety InstructionsOperating Instructions Operation Design Features and AdvantagesGeneral Description Recommended ProcessesFigure B.1 Case Front Controls Controls and SettingsOperation Operating Steps Welding OperationTable of Contents Accessories Section OPTIONS/ACCESSORIES AccessoriesFactory Installed Options Field Installed OptionsTable of Contents Maintenance Section Routine and Periodic Maintenance MaintenanceFigure D.1 General Component Locations Idealarc R3R Table of Contents Theory of Operation Section Input Line Voltage Contactor and Main Transformer Theory of OperationFigure E.3 Output RECTIFICATION, CONTROL, and Feedback Output Rectification CONTROL, and FeedbackOptional Polarity Switch and Pocket Amptrol Circuits Protective Devices and Circuits Figure E.5 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 GuideSCR/Diode Pocket Amptrol Circuit Input Contactor Output Problems Welding Problems Materials Needed DescriptionInput Contactor Test Test ProcedureRemoved Test for Contact Continuity Description Figure F.3 DC Coil Input Contactor Connections Removed Control Transformer T2 Voltage Test Figure F.5 Control Transformer and Lead Locations Control Transformer T2 Voltage TestTroubleshooting & Repair Main Transformer T1 Voltage Test Main Transformer T1 Voltage Test Figure F.8 Main Secondary Lead Test Points Table F.1 Phase Angle Winding TestFigure F.9 Control Board G2206 Test Points Static SCR/DIODE Rectifier Bridge Test Static SCR/DIODE Rectifier Bridge Test Figure F.13 Snubber Board M15370 Plug P5 Location Static SCR/DIODE Rectifier Bridge TestSCR Test Active SCR Test Active SCR Test Figure F.20 SCR Tester Circuit and SCR Connections Active SCR TestPocket Amptrol Circuit Test Figure F.21 T3 Transformer and Leads Pocket Amptrol Pocket Amptrol Circuit TestFigure F.22 Pocket Amptrol Board Plug P6 and P7 Location Figure F.23 Sensing Resistor R4 Scope Settings Maximum Output Setting no LoadNormal Open Circuit Voltage Waveform Typical Output Voltage Waveform Machine Loaded CH1 Typical SCR Gate Voltage WaveformONE Output SCR not Functioning Abnormal Output Voltage WaveformInput Contactor CR1 CLEANING/REPLACEMENT Cleaning Procedure Input Contactor CR1 CLEANING/REPLACEMENTContactor Replacement 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 AssemblyReassembly TroubleshootingSCR Removal and Replacement Special Instructions SCR Removal and ReplacementFigure F.29 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 Heat Sinks Mounting of Stud Type Diodes to AluminumMain Transformer Removal and Replacement Removal of Lift Bail Main Transformer Removal & ReplacementFigure F.34 Choke Removal Removal of Choke and TOP Iron AssemblyFigure F.35 Epoxy MIX Application Areas Reassembly of Transformer CoilsFigure F.36 Coil Lead Placement Figure F.38 Secondary Lead Trim and Weld Detail Reassemble the Lift Bail Reassembling the Main Transformer Into the MachineInput Idle Amps and Watts Retest After Repair R3ROpen Circuit Voltages Welding Output Load TestWelding Output Terminals 63/69VDC 61/66VDC Welding Output Terminals 64/72VDC 61/69VDC Idealarc R3R Electrical Diagrams Idealarc R3R Electrical Diagrams DIAGRAMSELECTRICALG-4 Idealarc R3R-400, 500-I, 500 & 600-I Wiring Diagram Pocket Amptrol Schematic Snubber Board Schematic & Layout R3R-300 Control PC Board R3R-400 Control PC Board R3R-500 Control PC Board