Lincoln Electric SVM188-A service manual Volts

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F-37

TROUBLESHOOTING AND REPAIR

F-37

ABNORMAL OPEN CIRCUIT VOLTAGE WAVEFORM

CONSTANT VOLTAGE INNERSHIELD

ONE OUTPUT SCR NOT FUNCTIONING

	0 volts
20V	2ms

This is NOT the typical DC open cir- cuit voltage waveform. One output SCR is not functioning. Note the “gap” in the waveform. One SCR gate is disconnected to simulate an open or non-functioning output SCR. Each vertical division represents 20 volts and each horizontal division rep- resents 2 milliseconds in time.

Note: Scope probes connected at

machine output terminals: (+) probe to positive terminal, (-) probe to nega- tive high inductance terminal.

SCOPE SETTINGS

Volts/Div	20V/Div.
Horizontal Sweep	2 ms/Div.
Coupling	DC
Trigger	Internal

DC-600

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Contents DC-600 ISAFETYi Electric Shock can kill SafetyFumes and Gases Can be dangerousFor Electrically Powered equipmentSûreté Pour Soudage a L’Arc Précautions DE SûretéElectromagnetic Compatibility EMC Safety Master Table of Contents for ALL Sections Table of Contents Installation Section Technical Specifications DC-600 InstallationSelect Proper Location Safety PrecautionsElectric Shock can Kill Ground Connection Fuse and Wire SizesElectrical Input Connections Connection for Highest Rating Plate VOLTAGE, 50 or 60 HZ Reconnect ProcedureConnection for 440 Volts 50 or 60 HZ V 60HZ See Machine Rating Plate for Required Input Supply Voltage Connections Output ConnectionsELECTRODE, Work and #21 Lead Terminal Strip 2 T.S.2 Auxiliary Power Control ConnectionsTerminal Strip 1 T.S.1 DC-600 Table of Contents Operation Section Operation Safety PrecautionsRecommended Processes and Equipment Design Features AdvantagesGeneral Description OFF Input Power Meanings of Graphical Symbols on Case FrontWelding Capability Output Control Output Voltage CurrentControls and Settings Meaning of Graphical Symbol for Ground CON- NectionOVERLOAD, OVERCURRENT, and Fault Protection Auxiliary Power in MS-RECEPTACLEOperating Steps Remote Control of Machine OperationWelding Procedure Recommendations Remote NA-3 Automatic Wire FeederLN-7 and Other Constant Wire Feeders LN-8 or LN-9 SEMI-AUTOMATIC Wire FeederDC-600 Table of Contents Accessories Section Wire Feeders and Tractors AccessoriesFactory or Field Installed Options Field Installed OptionsFigure C.2 MULTI-PROCESS Switch Cable Connections Accessories Table of Contents Maintenance Section Routine and Periodic Maintenance MaintenanceSafety Precautions Electric Shock can Kill 1TABLE of CONTENTS-THEORY of Operation Section E-1 Input Circuit and Main TRANS- Former Theory of OperationFiring Board Firing CIRCUIT, Control CIR- Cuit and RectificationRectification Thermal Protection SCR Operation DC-600 1TABLE of Contents Troubleshooting and Repair F-1 HOW to USE Troubleshooting Guide 2TROUBLESHOOTING and REPAIRF-2PC Board Troubleshooting Procedures Troubleshooting and RepairControl Feeder. See Protective Devices Check all three phase input Output Control J1,Pin2. See Wiring Diagram Wiring Diagram Materials Needed PC Board Troubleshooting GuideTest Description PC Board Troubleshooting Guide Figure F.2 Control Board LEDs Control BoardDC-600 Internal Trigger Circuit Test Internal Trigger Circuit Test Procedure75 76 Internal Trigger Circuit TestDC-600 Firing Board Test Firing Board Test Control Board Test Figure F.7 Control Board Control Board TestMain Transformer Voltage Test Figure F.8 Input Contactor and Reconnect Panel Main Transformer Voltage TestFigure F.9 Transformer Secondaries Main Transformer Voltage Test Control Transformer Test Control Transformer Test ProcedureInput Contactor Test Voltage Test Input Contactor TestSCR Bridge Test SCR Bridge Test Anode Cathode Remove Insulating PaintActive Test Scope Settings Maximum Output Setting no Load Minimum Output Setting no Load 35TROUBLESHOOTING and REPAIRF-35 2V/Div Volts DC-600 Input Contactor CR1 CLEANING/REPLACEMENT Contactor Replacement Procedure Input Contactor CLEANING/REPLACEMENT ProcedureCleaning Procedure SCR Rectifier Bridge Removal and Replacement Procedure Removal and Replacement Procedure 42TROUBLESHOOTING and REPAIRF-42Removal Procedure SCR Rectifier BridgeInsulator Lock Washer Plain Washer Output Snubber Lead Replacement ProcedureDC-600 Main Transformer and Choke Removal and Replacement Main Transformer and Choke Removal and ReplacementRemoval Procedure Weld Maximum Open Circuit Voltages Input Idle Amps and WattsDC-600 Table of Contents Diagram Section Electrical Diagrams Wiring Diagram 230/460/575 Volt Machines G3506-1 Schematic Complete Machine G3575 Schematic Control PC Board G3408-1 Control PC Board Assembly G3409-1 Schematic Firing PC Board G3741-1