Lincoln Electric R3R-300 Abnormal Output Voltage Waveform, ONE Output SCR not Functioning

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F-38

F-38

TROUBLESHOOTING & REPAIR

ABNORMAL OUTPUT VOLTAGE WAVEFORM

ONE OUTPUT SCR NOT FUNCTIONING

0 volts

50 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 50 volts and each horizontal division repre- sents 5 milliseconds in time. The machine was loaded with a resis- tance grid bank.

Note: Scope probes connected at

machine output terminals: (+) probe to positive terminal, (-) probe to neg- ative terminal. (R3R 500 machine)

SCOPE SETTINGS

Volts/Div	50V/Div.
Horizontal Sweep	5 ms/Div.
Coupling	DC
Trigger	Internal

IDEALARC R3R

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Contents Idealarc R3R-300, -400 Safety California Proposition 65 WarningsElectric Shock can kill Cylinder may explode if damaged Précautions DE Sûreté Master Table of Contents for ALL Sections Table of Contents Installation Section Installation Technical Specifications Idealarc R3R-300Technical Specifications Idealarc R3R-400 Technical Specifications Idealarc R3R-500 Safety Precautions Select Suitable LocationLifting TiltingInput Connections Ground ConnectionInput Supply Connections Input Wire and Fuse Size Figure A.2 Input Power Supply ConnectionsReconnect Procedure Input Supply Connection DiagramOutput Connections STICK, TIG, AIR/CARBON ARC Cutting Return to SectionIdealarc R3R Table of Contents Operation Section Safety Instructions OPERATIONB-2Operating Instructions Design Features and Advantages OperationGeneral Description Recommended ProcessesControls and Settings Figure B.1 Case Front ControlsOperation Welding Operation Operating StepsTable of Contents Accessories Section Accessories OPTIONS/ACCESSORIESFactory Installed Options Field Installed OptionsTable of Contents Maintenance Section Maintenance Routine and Periodic MaintenanceFigure D.1 General Component Locations Idealarc R3R Table of Contents Theory of Operation Section Theory of Operation Input Line Voltage Contactor and Main TransformerOutput Rectification CONTROL, and Feedback Figure E.3 Output RECTIFICATION, CONTROL, and FeedbackOptional Polarity Switch and Pocket Amptrol Circuits Protective Devices and Circuits SCR Operation Figure E.5 SCR OperationTable of Contents Troubleshooting & Repair Section Troubleshooting & Repair HOW to USE Troubleshooting GuidePC Board Troubleshooting Procedures PC Board can be damaged by static electricityTroubleshooting Guide Output ProblemsSCR/Diode Pocket Amptrol Circuit Input Contactor Output Problems Welding Problems Description Materials NeededTest Procedure Input Contactor TestRemoved Test for Contact Continuity Description Figure F.3 DC Coil Input Contactor Connections Removed Control Transformer T2 Voltage Test Control Transformer T2 Voltage Test Figure F.5 Control Transformer and Lead LocationsTroubleshooting & Repair Main Transformer T1 Voltage Test Main Transformer T1 Voltage Test Figure F.8 Main Secondary Lead Test Points Phase Angle Winding Test Table F.1Figure F.9 Control Board G2206 Test Points Static SCR/DIODE Rectifier Bridge Test Static SCR/DIODE Rectifier Bridge Test Static SCR/DIODE Rectifier Bridge Test Figure F.13 Snubber Board M15370 Plug P5 LocationSCR Test Active SCR Test Active SCR Test Active SCR Test Figure F.20 SCR Tester Circuit and SCR ConnectionsPocket Amptrol Circuit Test Pocket Amptrol Circuit Test Figure F.21 T3 Transformer and Leads Pocket AmptrolFigure F.22 Pocket Amptrol Board Plug P6 and P7 Location Figure F.23 Sensing Resistor R4 Maximum Output Setting no Load Scope SettingsNormal Open Circuit Voltage Waveform Typical Output Voltage Waveform Machine Loaded Typical SCR Gate Voltage Waveform CH1Abnormal Output Voltage Waveform ONE Output SCR not FunctioningInput Contactor CR1 CLEANING/REPLACEMENT Input Contactor CR1 CLEANING/REPLACEMENT Cleaning ProcedureContactor Replacement Procedure FAN Motor and Blade Removal and Replacement FAN Motor and Blade Removal and Replacement ProcedureSCR/DIODE Rectifier Assembly Removal and Replacement SCR/DIODE Rectificer Assembly Removal and ReplacementTroubleshooting ReassemblySCR Removal and Replacement SCR Removal and Replacement Special InstructionsProcedure for the 1/2 Inch Wide Spring Figure F.29 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.34 Choke RemovalReassembly of Transformer Coils Figure F.35 Epoxy MIX Application AreasFigure F.36 Coil Lead Placement Figure F.38 Secondary Lead Trim and Weld Detail Reassembling the Main Transformer Into the Machine Reassemble the Lift BailRetest After Repair R3R Input Idle Amps and WattsOpen 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