Lincoln Electric SVM170-A service manual Static SCR Rectifier Assembly Test

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F-20	TROUBLESHOOTING AND REPAIR	F-20
	STATIC SCR RECTIFIER ASSEMBLY TEST (continued)

FIGURE F.3 — REMOVE PLUGS J6 AND J5 TO PERFORM STATIC RECTIFIER ASSEMBLY TEST.

J6

J5

J3

J8

J1

J4

J2

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TEST PROCEDURE

1.Disconnect main AC input power to the machine.

2.Remove the case top and side panels with a 3/8 in. nutdriver.

3.Remove the tool tray with a 5/16 in. nut- driver.

4.Verify that the capacitors have completely discharged with a volt- ohmmeter.

5.Disconnect plugs J6 and J5 from the control board . This electrically isolates the SCR bridge assembly. See Figure F.3.

POWER MIG 255C

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Contents Power MIG 255C Safety California Proposition 65 WarningsElectric 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 Table of Contents Installation SectionTechnical Specifications Power MIG 255C Safety Precautions Uncrating the Power MIG 255CInput POWER, Grounding and Connection Diagrams LocationInstallation Figure A.2 Triple Voltage Machine Input Connections GUN and Cable Installation Auxiliary Power ReceptaclesShielding GAS Table of Contents Operation Section OperationOPERATIONB-2 Wear eye, ear and body protec- tionProduct Description Recommended Processes and EquipmentWelding Capability LimitationsWire Size Conversion Parts Wire Drive RollDescription of Controls Procedure for Changing Wire Reel Loading Readi REELS, Spools or CoilsDrive and Idle Roll Sets Feeding Wire Electrode Idle Roll Pressure SettingWire Drive Configuration To Start the WelderFigure B.4 When Timer Option is not installed Instructions to Enter Slow RUN-INInstructions to Enter Fast RUN-IN Making a WeldAvoiding Wire Feeding Problems Wire Feed Overload ProtectionFAN Control Input Line Voltage ProtectionWelding Thermal Overload Protection Overcurrent ProtectionAccessories Table of Contents Accessories SectionDrive Roll Kits Magnum GUN Connection KITK363P READI-REEL Adapter Dual Cylinder Mounting KIT K1702-1Operating Instructions for Timer KIT Connecting the Spool GUN to the Power MIG 255CK1738-1 Spool Gun Hanger Accessory Spool GUNMaking a Weld with the Prince XL Spool GUN Making a Weld with the Magnum SG Spool GUNSG Spool Gun Wire Feed Speed Power MIG Maintenance Table of Contents Maintenance SectionGUN Tubes and Nozzles General Maintenance GUN Cable CleaningContact TIP and GAS Nozzle Installation Liner Removal and ReplacementGUN Handle Disassembly Table D.1MAINTENANCED-4 English Metric DescriptionTable of Contents Theory of Operation Section Theory of OperationInput Line Voltage Main TransformerOutput Rectification Feedback ControlConstant Voltage Output Figure E.4 Constant Voltage OutputWire Drive Motor FeedbackWire Feed Overload Protection Thermal and Overload ProtectionSCR Operation Figure E.6 SCR OperationPower MIG 255C Troubleshooting and Repair Table of Contents Troubleshooting and Repair Section2TROUBLESHOOTING and REPAIRF-2 HOW to USE Troubleshooting GuidePC Board Troubleshooting Procedures Troubleshooting Guide Output ProblemsProblems Possible Areas Symptoms Misadjustments Course of ActionTrolyte in these capacitors is Toxic. Avoid contact with anyPerform the SCR Rectifier Function Problems Wire Feeding Problems Welding Problems Welding Problems Test Procedures Main Transformer TestTest Description Materials NeededTest Procedure ON/OFF Power Switch will be hot during these tests115VAC 16J5 8J5206 3J5 Rectifier Diode Bridge Test 16TROUBLESHOOTING and REPAIRF-16 Figure F.2 G3521 Rectifier Diode Bridge Location208 206 28 VAC 209 354 206 36 VDCPower MIG 255C Static SCR Rectifier Assembly Test Static SCR Rectifier Assembly Test Active SCR Rectifier Assembly Test Power MIG 255C Active SCR Rectifier Assembly Test Active SCR Rectifier Assembly Test Figure F.7 Location Leads X2 Figure F.8 Wire Drive Motor and Tachometer Feedback Test Wire Drive Motor and Tachometer Feedback Test 4J1Test for Supply Voltage to Tachometer 515B 206B 15 VDC 5J1 1J1Test for Feedback Voltage to Control Board 555 206B To 3.5 VDC 6J1 1J1Normal Open Circuit Voltage Waveform VoltsMachine Loaded to 250 Amps AT 26 VDC Scope Settings Typical Output Voltage Waveform Machine LoadedMachine Loaded to 220 Amps AT 22 VDC Scope Settings Troubleshooting and Repair Typical SCR Gate Voltage Waveform Power MIG 255C Component Replacement Procedures Control PC Board Removal and ReplacementDescription Removal and Replacement ProcedureFigure F.11 Control Board Mounting Power MIG 255C Wire Drive Assembly Removal and Replacement Wire Drive Assembly Removal and Replacement Procedure Power MIG 255C SCR Output Rectifier Removal and Replacement SCR Output Rectifier Removal and Replacement Figure F.15 Right Heat Sink Lead Disconnection Power MIG 255C Capacitor Bank Removal and Replacement Capacitor Bank Removal and Replacement Main Transformer and Output Choke Removal and Replacement 52TROUBLESHOOTING and REPAIRF-52 Main Transformer and Output ChokeTOC Power MIG 255C FAN Motor Assembly Removal and Replacement FAN Motor Assembly Removal and Replacement Wire Speed Range Retest After RepairOpen Circuit Voltage Input Volts/HertzPower MIG 255C Electrical Diagrams Section Section G-1Electrical Diagrams Wiring Diagram Entire Machine Code 11192 L12464Wiring Diagram Entire Machine Code 11218 L12506 Schematic Entire Machine G4752 Schematic Control PC Board G4823-2D1 Sheet Electrical Diagrams Electrical Diagrams PC Board Assembly Control G4824-2D1 Item Used with QTY Part Number DescriptionSchematic Display PC Board L10951 PowermigPC Board Assembly Display L10952 Lincoln Electric COSVM Error Reporting Form