Lincoln Electric SVM 117-A service manual Typical SCR Gate Voltage Waveform

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F-26	TROUBLESHOOTING & REPAIR	F-26
	TROUBLESHOOTING & REPAIR

TYPICAL SCR GATE VOLTAGE WAVEFORM

SCOPE SETTINGS

This is a typical SCR gate pulse voltage
waveform. The machine was in an open cir-	Volts/Div	. .2 V/Div.
cuit condition (no load) and operating prop-
erly. Note that each vertical division repre-	Horizontal Sweep	.5 ms/Div.
sents 2 volts and each horizontal division
represents 5 milliseconds in time.	Coupling	. . . . .DC.
Note: Scope probes connected at Plug J3	Trigger	. .Internal.
on the control board. The (+) probe to lead
G2, and the (-) probe to lead 204.

WIRE-MATIC 250

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Contents Safety Depends on You WIRE-MATICARC Welding can be hazardous SafetyCylinder may explode if damaged Iii Electric and MAG- Netic FieldsSûreté Pour Soudage a L’Arc Précautions DE SûretéWIRE-MATIC Table of Contents Table of Contents Installation Type 750C Copper Duty Cycle Amps Volts at Rated AmpsCurrent Range Fuse SuperlagStacking Safety PrecautionsSelect Proper Location Input ConnectionsInput Power Connections and Ground Connections Fuse and Wire SizesConnect Shielding GAS Figure A.4 Input Air Supply Connections Reconnect ProcedureFigure A.5 Reconnect Diagram For 208/230/1/60 Machines Output Polarity Connection InstallationInstall the Work Clamp Connect Output Components GUN Liner and ContactGUN and Cable Installation Wire Size Conversion PartsWIRE-MATIC Operation General Description Safety InstructionsWELDING, Cutting Recommended Processes and Equipment Design Features AdvantagesUnit Features Power Source FeaturesDuty Cycle Amps Volts Wire Feeder FeaturesMachine Capability LimitationsFigure B.1 Operator Controls Controls and SettingsProcedure for Changing Drive Roll Using the Wire Drive RollLoading the Wire Reel Feeding Electrode Proper Wire FeedingTo mount 10 to 30 lb. spools 8 and 12 diameter Operating Steps Setting Idle Roll PressureStarting the Welder Making a Weld WIRE-MATIC Accessories Installing the K607-1 Spool GUN Adapter KIT OPTIONS/ACCESSORIESK607-1 Spool GUN Adapter KIT Spool GUN Module Board InstallationReturn Return to Section TOC Spool GUN Connection BOX InstallationSpool GUN Preparation Spool GUN ConnectionMaking the Weld Making a Weld with the Spool GUN Adapter K607-1 InstalledTimer KIT K585-1 To Make Spot Plug Welds Steel Wire Sizes Part NumberAluminum Wire Sizes Drive Roll KitsMaintenance Perform the following daily Routine and Periodic MaintenanceMaintenance DROP-IN Reel Spindle and Clips Contact TIP and GAS Nozzle InstallationCable Cleaning Drive Rolls and Guide Tubes GUN Tubes and NozzlesFigure D.2 Liner maintenance Liner Removal ReplacementTo open up the handle GUN Handle DisassemblyDescription English Size Metric Size WIRE-MATIC Theory of Operation Transformer 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 Troubleshooting & Repair Recommended Course of Action HOW to USE Troubleshooting GuideElectric Shock can kill PC Board Troubleshooting ProceduresBoard can be dam- aged by static electricity Main Transformer Rectifier Assembly Test To Section TOC Perform the SCR Rectifier Perform the Wire Drive Motor Trolyte in these capacitors is Liquid elecPerform the Output Rectifier Test Description Main Transformer TestMaterials Needed ON/OFF Power Switch will be hot during these tests Main Transformer Test Test ProcedureMain Transformer Test 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 ReplacementMaterials Needed Removal and REPLACE- Ment Procedure Wire Drive Assembly Removal and Replacement Figure F.11 Wire Drive Assembly Removal Wire Drive Assembly Removal and Replacement 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 Electrical Diagrams Spool GUN Option Wiring Diagram 208/230 Code To Section Available from Lincoln Control PC Board G2332 Layout