Lincoln Electric SVM 119-A service manual Machine Loaded to 220 Amps AT 22 VDC Scope Settings

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F-24	TROUBLESHOOTING & REPAIR	F-24
	TROUBLESHOOTING & REPAIR

ABNORMAL OUTPUT VOLTAGE WAVEFORM - MACHINE LOADED

ONE OUTPUT SCR NOT FUNCTIONING

MACHINE LOADED TO 220 AMPS AT 22 VDC

SCOPE SETTINGS

This is NOT a typical DC output voltage
waveform. One output SCR is not function-	Volts/Div	.20 V/Div.
ing. Note the increased ripple content. One
SCR gate was disconnected to simulate an	Horizontal Sweep	.5 ms/Div.
open or non-functioning output SCR. Each
vertical division represents 20 volts and	Coupling	. . . . .DC.
each horizontal division represents 5 mil-
liseconds in time. The machine was loaded	Trigger	. .Internal.
with a resistance grid bank.
Note: Scope probes connected at machine
output terminals: (+) probe to electrode, (-)
probe to work.

WIRE-MATIC 255

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Contents Safety Depends on You WIRE-MATICFumes and Gases can be dangerous SafetyElectric Shock can kill ARC Rays can burnWelding Sparks can cause fire or explosion Cylinder may explode if damagedElectric and MAG- Netic Fields May be dangerousIii Sûreté Pour Soudage a L’Arc Précautions DE SûretéWIRE-MATIC Table of Contents Table of Contents Table of Contents Installation Section InstallationTechnical Specifications Wire-Matic-255 Stacking Safety PrecautionsSelect Proper Location Input ConnectionsFuse and Wire Sizes Connect Shielding GAS Figure A.4 Input Gas Supply Connections Reconnect ProcedureFigure A.5 Reconnect Diagram For 208/230/1/60 Machines Connections Connect Output ComponentsGUN and Cable Installation Wire Size Conversion PartsWIRE-MATIC Operation Table of Contents Operation SectionSafety Instructions General DescriptionWELDING, Cutting Recommended Processes and Equipment Design Features AdvantagesMachine Capability LimitationsDuty Cycle Amps Volts Figure B.1 Operator Controls Controls and SettingsFigure B.2 Wire Reel Loading Using the Wire Drive RollFeeding Electrode Operating Steps Setting Idle Roll PressureMaking a Weld WIRE-MATIC Table of Contents Accessories Section AccessoriesOPTIONS/ACCESSORIES Magnum GUN Connection KIT Optional K466-6K672-1 Spool GUN Adapter KIT Making a Weld with the Spool GUN Adapter K672-1 Installed Timer KIT Installation Optional K585-1 Timer KIT K585-1K363P READI-REEL Adapter Drive Roll Kits64 1.2mm Aluminum Feeding KIT K673-1 K468 8 Spool AdapterDual Cylinder Mounting KIT K671-1 Table of Contents Maintenance Section MaintenancePerform the following daily Routine and Periodic MaintenanceMaintenance GUN Tubes and Nozzles Cable CleaningContact TIP and GAS Nozzle Installation Drive Rolls and Guide TubesFigure D.2 Liner maintenance Liner Removal ReplacementTo open up the handle GUN Handle DisassemblyDescription English Size Metric Size WIRE-MATIC Theory of Operation Table of Contents Theory of Operation SectionTransformer Input Line Voltage and MainFeedback Control Output RectificationFigure E.4 Constant Voltage Output Constant Voltage OutputFeedback Wire Drive MotorThermal Protection Figure E.6 SCR Operation SCR OperationWIRE-MATIC Table of Contents Troubleshooting & Repair Section Troubleshooting & RepairRecommended Course of Action HOW to USE Troubleshooting GuidePC Board Troubleshooting Procedures Electric Shock can killBoard can be dam- aged by static electricity Main Transformer Rectifier Assembly Test To Section TOC SCR Rectifier Perform the Wire Drive Motor Trolyte in these capacitors is Liquid elecPerform the Output Rectifier Main Transformer Test Test DescriptionMaterials Needed ON/OFF Power Switch will be hot during these tests Main Transformer Test Test ProcedureLead Plug Location Static SCR Rectifier Assembly Test Leads Figure F.4 SCR 1 Test Points Active SCR Rectifier Assembly Test Leads SCR connections Figure F.7 SCR Tester CircuitWire Drive Motor and Tachometer Feedback Test Wire Drive Motor and Tachometer Feedback Test Test Procedure Test for Feedback Voltage to the Control Board Test for Supply Voltage to TachometerNormal Open Circuit Voltage Waveform Scope SettingsTypical Output Voltage Waveform Machine Loaded Machine Loaded to 250 Amps AT 26 VDC Scope SettingsMachine Loaded to 220 Amps AT 22 VDC Scope Settings Troubleshooting & Repair Typical SCR Gate Voltage Waveform Removal and Replacement Procedure Control PC Board Removal and ReplacementRemoval and REPLACE- Ment Procedure Wire Drive Assembly Removal and Replacement Figure F.11 Wire Drive Assembly Removal ProcedureSCR Output Rectifier Removal & Replacement Disconnection Heat Sink Lead Right side heat sink See Figure F.14Capacitor Bank Removal and Replacement Components Bank Removal ReplacementMain Transformer Removal and Replacement Power Switch FAN Motor and FAN Removal and Replacement Figure F.16 Fan Motor and Fan Removal Components FAN Motor and FAN Removal and Replacement ProcedureTroubleshooting & Repair 230/60 375 Wire Speed RangeOpen Circuit Voltage Input Volts/HertzWIRE-MATIC Table of Contents Electrical Diagrams Section WIRE-MATIC Wiring Diagram 208/230 Code Electrical DiagramsWiring Diagram 230/460/575 Code Wire Matic 255 230 / 460Control PC Board G2803 Schematic Control PC Board G2803 Layout Wirematic 255 Control