Lincoln Electric SVM132-A service manual Potentiometer Replacement

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F-24	TROUBLESHOOTING AND REPAIR	F-24
	TROUBLESHOOTING AND REPAIR

POTENTIOMETER REPLACEMENT

WARNING

Service and repair should be performed only by Lincoln Electric factory trained per- sonnel. Unauthorized repairs performed on this equipment could result in danger to the technician or the machine operator and will invalidate your factory warranty. For your safety and to avoid electrical shock, please observe all safety notes and precau- tions detailed throughout this manual.

If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact the Lincoln Electric service department for technical troubleshooting assistance before you proceed.

Call (800) 833-9353 (WELD).

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MATERIALS NEEDED

5/16 in. nutdriver 1/2 in. wrench 5/64 in. Allen wrench

Small slothead screwdriver Soldering iron and solder

This procedure takes approximately 10 minutes to perform.

LN-8

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Contents LN-8 Semiautomatic Wire Feeder Safety LN-8Electric Shock can kill Welding Sparks can cause fire or explosion IiiPrécautions DE Sûreté Sûreté Pour Soudage a L’ArcMaster Table of Contents for ALL Sections Installation LN-8 with K377 Electrode DiameterLN-8 with K303 LN-8 with K378LN-8N and LN-8NE Power Source ConnectionsTable A.1 Work Lead Specifications Power Source Selection Switch Variable Voltage PC Board LN-8S and LN-8SE and Converted LN-8N and LN-8NEPower Source Connection Diagrams Table A.2 LN-8 Power Source Connection DiagramsSection TOC Installation TOC 9A-9 Figure A.5 Connection of LN-8 to R3S-250 and R3S-32510A-10 Figure A.6 Connection of LN-8 to DC-600Power Source To LN-8 Input Cable Plug Control Cable LN-8 for Same Polarity Operation LN-8 for Opposite Polarity Operation Shock Can KillFigure A.10 for Power Sources Other than Lincoln Electric 14A-14LN-8N and LN-8S Cable Clamp Conductor Electrode Wire Reel BasecontrolInput Cable Connections LN-8NE and LN-8SELocking Connections to Wire FeederExtension Tube Connector ScrewFigure A.14 Wire Feeder Handle Installation SELF-TAPPING Screw Hinge HandleLN-8S and LN-8SE Continuous Flux Feed Submerged ARC Handling ProceduresGUN and Cable Assemblies GeneralOperation Constant Current Controls Safety InstructionsControls and Their Functions Gouging SparksConstant Voltage Controls Current Controls VoltageCircuit Protection Avoiding Ground Lead Protector GLP ActivationWire Feed Rolls and Guide Tubes Figure B.3 Wire Feed Rolls and Guide Tube InstallationSetting for CV or CC Power Sources Voltage Power Source Welding with a ConstantMounting a 50 or 60 lb Coil Slots Coil ReelAdapter Wire Reel Loading K1524-1 Universal Wire Reel StandK363-P READI-REEL Adapter Innershield Coils To Mount 10 to 44 lb 4.5 to 20 kg Spools12 in./300 mm Diameter or 14 lb 6 kg READI-REELS a K438 READI-REEL Adapter Must be UsedBrass Blocks Hand Crank ARM Feeding Electrode to the LN-8N or LN-8SFeeding Electrode to the LN-8NE or LN-8SE with Extension Flux Tank Loading Slow Acceleration Starting Code 7926 and AboveAccessories Table C.1 LN-8 Wire Feeder Accessories GeneralK178 Mounting Platform K161 Mechanized Travel Power PackK163 Undercarriage Requires K303, K377, or K378 K58 Magnetic SeparatorReel Mounting Accessories Welding Guns Welding GUN Accessories Constant Current Conversion PartsLN-8 Maintenance Table of Contents Maintenance SectionRoutine Maintenance Periodic Maintenance Table of Contents Theory of Operation Section Theory of OperationPower Input Circuits General DescriptionGUN Trigger and 1CR Relay Contact Control Circuits Figure E.2 GUN Trigger and 1CR Contact Control CircuitsFuse Field Applied Later CYCLE, the SCR Output Is Decreased SCR Operation5E-5 LN-8 Troubleshooting and Repair HOW to USE Troubleshooting Guide Return to Return to Section TOCTroubleshooting & Repair PC Board Troubleshooting ProceduresTroubleshooting Guide Problems SymptomsFunction Problems Transformer Test Perform the 1CR Relay Test Feeding Problems Welding Problems LN-8 Electrical Sequence of Operation Figure F.1 LN-8 Electrical Sequence of Operation Trigger Transformer Test Test DescriptionTrigger Transformer Test Internal Voltage Test Circuit Applied Breaker ConnectorReceptacle Control BoardInternal Voltage Test Table F.1 Voltage Test Points1CR Relay Test 1CR Relay Test 1CR Relay Test Table F.2 Relay Test Terminal ConnectionsDrive Motor Test Drive Motor Test Figure F.6 GUN Terminal Jumper Locations 1CRTo further check the drive motor Table F.3 Drive Motor Test PointsPotentiometer Replacement Repair Procedure Circuit Breaker Replacement Ground Lead Protector Switch Mount Flatwasher Lockwasher NUT Retaining NUTGround Lead Protector Push Button Switch Replacement Ground Lead Protector Push Button Trigger Transformer Replacement Relay PC Board Roundhead Screw Insulation Sheet Trigger Transformer NUTPC Board Replacement Figure F.10 PC Board Locations Control PC Board Variable Voltage PC Board Relay PC BoardRelay Board Removal Control PC Board Replacement Wire Drive Assembly and Component Replacement Green Ground Yellow BlackWhite Blue TWOShunt #568 #567Motor Gearbox Insulation Sheet Mounting PlateTOC Retest After Repair Electrical Diagrams LN-8N, -8NE, -8S, and -8SE Wiring Diagram Connection Schematic Source Power to WorkOperating Schematic 1CR Wire Feed Motor FieldControl Board L5767 Schematic Variable Voltage Board L5039 Schematic Control Board L5767 Layout ControlVariable Voltage Board L5039 Layout SVM Error Reporting Form