Lincoln Electric SVM188-A service manual Minimum Output Setting no Load

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F-34

TROUBLESHOOTING AND REPAIR

F-34

NORMAL OPEN CIRCUIT VOLTAGE WAVEFORM

CONSTANT VOLTAGE INNERSHIELD

MINIMUM OUTPUT SETTING – NO LOAD

0 volts

20V

2ms

This is the typical DC open circuit voltage waveform generated from a properly operating machine. Note that each vertical division represents 20 volts and that each horizontal divi- sion represents 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 Fumes and Gases SafetyElectric Shock can kill Can be dangerousPowered equipment For ElectricallyPrécautions DE Sûreté Sûreté Pour Soudage a L’ArcElectromagnetic Compatibility EMC Safety Master Table of Contents for ALL Sections Table of Contents Installation Section Installation Technical Specifications DC-600Select Proper Location Safety PrecautionsElectric Shock can Kill Ground Connection Fuse and Wire SizesElectrical Input Connections Reconnect Procedure Connection for Highest Rating Plate VOLTAGE, 50 or 60 HZConnection 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 Safety Precautions OperationRecommended Processes and Equipment Design Features AdvantagesGeneral Description Welding Capability Meanings of Graphical Symbols on Case FrontOFF Input Power Output Control Output Voltage CurrentMeaning of Graphical Symbol for Ground CON- Nection Controls and SettingsAuxiliary Power in MS-RECEPTACLE OVERLOAD, OVERCURRENT, and Fault ProtectionOperating Steps Remote Control of Machine OperationWelding Procedure Recommendations NA-3 Automatic Wire Feeder RemoteLN-8 or LN-9 SEMI-AUTOMATIC Wire Feeder LN-7 and Other Constant Wire FeedersDC-600 Table of Contents Accessories Section Factory or Field Installed Options AccessoriesWire Feeders and Tractors 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 Theory of Operation Input Circuit and Main TRANS- FormerFiring Board Firing CIRCUIT, Control CIR- Cuit and RectificationRectification Thermal Protection SCR Operation DC-600 1TABLE of Contents Troubleshooting and Repair F-1 2TROUBLESHOOTING and REPAIRF-2 HOW to USE Troubleshooting GuideTroubleshooting and Repair PC Board Troubleshooting ProceduresControl 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 Control Board Figure F.2 Control Board LEDsDC-600 Internal Trigger Circuit Test Procedure Internal Trigger Circuit TestInternal Trigger Circuit Test 75 76DC-600 Firing Board Test Firing Board Test Control Board Test Control Board Test Figure F.7 Control BoardMain Transformer Voltage Test Main Transformer Voltage Test Figure F.8 Input Contactor and Reconnect PanelFigure F.9 Transformer Secondaries Main Transformer Voltage Test Control Transformer Test Procedure Control Transformer TestInput Contactor Test Input Contactor Test Voltage TestSCR Bridge Test Anode Cathode Remove Insulating Paint SCR Bridge TestActive 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 Procedure 42TROUBLESHOOTING and REPAIRF-42Removal and Replacement Procedure SCR Rectifier BridgeReplacement Procedure Insulator Lock Washer Plain Washer Output Snubber LeadDC-600 Main Transformer and Choke Removal and Replacement Removal and Replacement Main Transformer and ChokeRemoval Procedure Weld Input Idle Amps and Watts Maximum Open Circuit VoltagesDC-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