Troubleshooting and Repair | Lincoln Electric SVM170-A instruction

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F-1		TROUBLESHOOTING AND REPAIR	F-1

		TABLE OF CONTENTS
		-TROUBLESHOOTING AND REPAIR SECTION-
Troubleshooting and Repair			Section F
	How to Use Troubleshooting Guide		F-2
	PC Board Troubleshooting Procedures		F-3
	Troubleshooting Guide		F-4
	Test Procedures		F-11
		Main Transformer Test	F-11
		Rectifier Diode Bridge Test	F-15
		Static SCR Rectifier Assembly Test	F-19
		Active SCR Rectifier Assembly Test	F-23
		Wire Drive Motor and Tachometer Feedback Test	F-27
	Oscilloscope Waveforms
		Normal Open Circuit Voltage Waveform	F-31
		Typical Output Voltage Waveform - Machine Loaded	F-32
		Abnormal Output Voltage Waveform - Machine Loaded One Output SCR Not Functioning . . .	F-33
		Abnormal Open Circuit Voltage Output Capacitor Bank Not Functioning	F-34
		Typical SCR Gate Voltage Waveform	F-35
	Component Replacement Procedures		F-37
		Control PC Board Removal and Replacement	F-37
		Wire Drive Assembly Removal and Replacement	F-41
		SCR Output Rectifier Removal and Replacement	F-45
		Capacitor Bank Removal and Replacement	F-49
		Main Transformer and Output Choke Removal and Replacement	F-51
		Fan Motor and Fan Removal and Replacement	F-55
	Retest After Repair		F-57

POWER MIG 255C

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Lincoln Electric SVM170-A service manual Table of Contents Troubleshooting and Repair Section

Contents

Power MIG 255C California Proposition 65 Warnings Safety Electric Shock can kill Iii Welding Sparks can cause fire or explosion Sûreté Pour Soudage a L’Arc Précautions DE Sûreté Master Table of Contents For ALL Sections Table of Contents Installation Section Installation Technical Specifications Power MIG 255C Uncrating the Power MIG 255C Safety PrecautionsInput POWER, Grounding and Connection Diagrams Location Installation Figure A.2 Triple Voltage Machine Input Connections Shielding GAS GUN and Cable InstallationAuxiliary Power Receptacles Operation Table of Contents Operation Section Wear eye, ear and body protec- tion OPERATIONB-2 Recommended Processes and Equipment Product DescriptionWelding Capability Limitations Description of Controls Wire Size Conversion PartsWire Drive Roll Drive and Idle Roll Sets Procedure for ChangingWire Reel Loading Readi REELS, Spools or Coils Idle Roll Pressure Setting Feeding Wire ElectrodeWire Drive Configuration To Start the Welder Figure B.4 Instructions to Enter Slow RUN-IN When Timer Option is not installedInstructions to Enter Fast RUN-IN Making a Weld Wire Feed Overload Protection Avoiding Wire Feeding ProblemsFAN Control Input Line Voltage Protection Overcurrent Protection Welding Thermal Overload Protection Table of Contents Accessories Section Accessories Magnum GUN Connection KIT Drive Roll KitsK363P READI-REEL Adapter Dual Cylinder Mounting KIT K1702-1 Connecting the Spool GUN to the Power MIG 255C Operating Instructions for Timer KITK1738-1 Spool Gun Hanger Accessory Spool GUN Making a Weld with the Magnum SG Spool GUN Making a Weld with the Prince XL Spool GUN SG Spool Gun Wire Feed Speed Power MIG Table of Contents Maintenance Section Maintenance GUN Cable Cleaning GUN Tubes and Nozzles General MaintenanceContact TIP and GAS Nozzle Installation Liner Removal and Replacement Table D.1 GUN Handle Disassembly English Metric Description MAINTENANCED-4 Theory of Operation Table of Contents Theory of Operation Section Main Transformer Input Line Voltage Feedback Control Output Rectification Figure E.4 Constant Voltage Output Constant Voltage Output Feedback Wire Drive Motor Thermal and Overload Protection Wire Feed Overload Protection Figure E.6 SCR Operation SCR Operation Power MIG 255C Table of Contents Troubleshooting and Repair Section Troubleshooting and Repair HOW to USE Troubleshooting Guide 2TROUBLESHOOTING and REPAIRF-2 PC Board Troubleshooting Procedures Output Problems Troubleshooting Guide Symptoms Misadjustments Course of Action Problems Possible AreasTrolyte in these capacitors is Toxic. Avoid contact with any Perform the SCR Rectifier Function Problems Wire Feeding Problems Welding Problems Welding Problems Main Transformer Test Test ProceduresTest Description Materials Needed ON/OFF Power Switch will be hot during these tests Test Procedure 16J5 8J5 115VAC 206 3J5 Rectifier Diode Bridge Test Figure F.2 G3521 Rectifier Diode Bridge Location 16TROUBLESHOOTING and REPAIRF-16 354 206 36 VDC 208 206 28 VAC 209 Power 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 4J1 Wire Drive Motor and Tachometer Feedback Test 515B 206B 15 VDC 5J1 1J1 Test for Supply Voltage to Tachometer 555 206B To 3.5 VDC 6J1 1J1 Test for Feedback Voltage to Control Board Volts Normal Open Circuit Voltage Waveform Typical Output Voltage Waveform Machine Loaded Machine Loaded to 250 Amps AT 26 VDC Scope Settings Machine Loaded to 220 Amps AT 22 VDC Scope Settings Troubleshooting and Repair Typical SCR Gate Voltage Waveform Power MIG 255C Description Component Replacement ProceduresControl PC Board Removal and Replacement Procedure Removal and Replacement Figure 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 Main Transformer and Output Choke 52TROUBLESHOOTING and REPAIRF-52 TOC Power MIG 255C FAN Motor Assembly Removal and Replacement FAN Motor Assembly Removal and Replacement Retest After Repair Wire Speed RangeOpen Circuit Voltage Input Volts/Hertz Power MIG 255C Section G-1 Electrical Diagrams Section Wiring Diagram Entire Machine Code 11192 L12464 Electrical Diagrams Wiring Diagram Entire Machine Code 11218 L12506 Schematic Entire Machine G4752 Schematic Control PC Board G4823-2D1 Sheet Electrical Diagrams Electrical Diagrams Item Used with QTY Part Number Description PC Board Assembly Control G4824-2D1 Powermig Schematic Display PC Board L10951 Lincoln Electric CO PC Board Assembly Display L10952 SVM Error Reporting Form