Lincoln Electric SVM132-A service manual Repair Procedure

Page 75

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F-25

TROUBLESHOOTING AND REPAIR	F-25

POTENTIOMETER REPLACEMENT (continued)

FIGURE F.7 – POTENTIOMETER REMOVAL

POTENTIOMETER

NUT

KNOB

INSULATION

LOCKWASHER

SET

SCREW

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REPAIR PROCEDURE

1.Remove input power to the LN-8

2.Using the 5/16 in. nutdriver, remove the screws from the left side cover assembly.

3.Using a 5/64 in. Allen wrench or slothead screwdriver, loosen the setscrew on the potentiometer knob and remove the knob from the potentiometer. Refer to Figure F.7.

4.Remove the nut and lockwasher holding the potentiometer to the left side cover assembly.

5.Remove the potentiometer and insulation sheet from the inside of the left side cover assembly.

6.Tag the three wires on the poten- tiometer so that they can be reat- tached in the same location from

LN-8

where they were removed. Unsolder the three wires from the potentiometer.

7.Solder the three wires to the new potentiometer on the correspond- ing terminals from where they were removed.

8.Place the new potentiometer and insulation sheet through the cover assembly from the inside. Ensure that the index pin in the poten- tiometer fits in the locating hole on the cover assembly. Install the lockwasher and nut on the poten- tiometer. Tighten the nut until it is snug.

9.Install the knob onto the poten- tiometer so the set screw aligns with the flat on the potentiometer. Tighten the set screw.

10.Install the screws that secure the left side cover assembly.

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Contents LN-8 Semiautomatic Wire Feeder LN-8 SafetyElectric Shock can kill Iii Welding Sparks can cause fire or explosionSûreté Pour Soudage a L’Arc Précautions DE SûretéMaster Table of Contents for ALL Sections Installation LN-8 with K378 Electrode DiameterLN-8 with K303 LN-8 with K377Power Source Connections Table A.1 Work Lead SpecificationsLN-8N and LN-8NE LN-8S and LN-8SE and Converted LN-8N and LN-8NE Power Source Selection Switch Variable Voltage PC BoardTable A.2 LN-8 Power Source Connection Diagrams Power Source Connection DiagramsSection TOC Installation TOC Figure A.5 Connection of LN-8 to R3S-250 and R3S-325 9A-9Figure A.6 Connection of LN-8 to DC-600 10A-10Power Source To LN-8 Input Cable Plug Control Cable LN-8 for Same Polarity Operation Shock Can Kill LN-8 for Opposite Polarity Operation14A-14 Figure A.10 for Power Sources Other than Lincoln ElectricLN-8NE and LN-8SE Cable Clamp Conductor Electrode Wire Reel BasecontrolInput Cable Connections LN-8N and LN-8SScrew Connections to Wire FeederExtension Tube Connector LockingSELF-TAPPING Screw Hinge Handle Figure A.14 Wire Feeder Handle InstallationGeneral Handling ProceduresGUN and Cable Assemblies LN-8S and LN-8SE Continuous Flux Feed Submerged ARCOperation Gouging Sparks Safety InstructionsControls and Their Functions Constant Current ControlsCurrent Controls Voltage Constant Voltage ControlsAvoiding Ground Lead Protector GLP Activation Circuit ProtectionFigure B.3 Wire Feed Rolls and Guide Tube Installation Wire Feed Rolls and Guide TubesSetting for CV or CC Power Sources Welding with a Constant Voltage Power SourceSlots Coil Reel Mounting a 50 or 60 lb CoilWire Reel Loading K1524-1 Universal Wire Reel Stand K363-P READI-REEL AdapterAdapter READI-REELS a K438 READI-REEL Adapter Must be Used To Mount 10 to 44 lb 4.5 to 20 kg Spools12 in./300 mm Diameter or 14 lb 6 kg Innershield CoilsFeeding Electrode to the LN-8N or LN-8S Feeding Electrode to the LN-8NE or LN-8SE with ExtensionBrass Blocks Hand Crank ARM Slow Acceleration Starting Code 7926 and Above Flux Tank LoadingAccessories General Table C.1 LN-8 Wire Feeder AccessoriesK58 Magnetic Separator K161 Mechanized Travel Power PackK163 Undercarriage Requires K303, K377, or K378 K178 Mounting PlatformReel Mounting Accessories Constant Current Conversion Parts Welding Guns Welding GUN AccessoriesLN-8 Table of Contents Maintenance Section MaintenanceRoutine Maintenance Periodic Maintenance Theory of Operation Table of Contents Theory of Operation SectionGeneral Description Power Input CircuitsFigure E.2 GUN Trigger and 1CR Contact Control Circuits GUN Trigger and 1CR Relay Contact Control CircuitsFuse Field SCR Operation 5E-5Applied Later CYCLE, the SCR Output Is Decreased LN-8 Troubleshooting and Repair Return to Return to Section TOC HOW to USE Troubleshooting GuidePC Board Troubleshooting Procedures Troubleshooting & RepairProblems Symptoms Troubleshooting GuideFunction 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 Test Description Trigger Transformer TestTrigger Transformer Test Internal Voltage Test Control Board ConnectorReceptacle Circuit Applied BreakerTable F.1 Voltage Test Points Internal Voltage Test1CR Relay Test 1CR Relay Test Table F.2 Relay Test Terminal Connections 1CR Relay TestDrive Motor Test Drive Motor Test 1CR Figure F.6 GUN Terminal Jumper LocationsTable F.3 Drive Motor Test Points To further check the drive motorPotentiometer Replacement Repair Procedure Circuit Breaker Replacement Retaining NUT Ground Lead Protector Switch Mount Flatwasher Lockwasher NUTGround Lead Protector Push Button Switch Replacement Ground Lead Protector Push Button Trigger Transformer Replacement Insulation Sheet Trigger Transformer NUT Relay PC Board Roundhead ScrewPC Board Replacement Control PC Board Variable Voltage PC Board Relay PC Board Figure F.10 PC Board LocationsRelay Board Removal Control PC Board Replacement Wire Drive Assembly and Component Replacement Blue TWO BlackWhite Green Ground Yellow#568 #567 ShuntGearbox Insulation Sheet Mounting Plate MotorTOC Retest After Repair Electrical Diagrams LN-8N, -8NE, -8S, and -8SE Wiring Diagram Source Power to Work Connection Schematic1CR Wire Feed Motor Field Operating SchematicControl Board L5767 Schematic Variable Voltage Board L5039 Schematic Control Control Board L5767 LayoutVariable Voltage Board L5039 Layout SVM Error Reporting Form