Lincoln Electric SVM157-A service manual Theory of Operation Section, Line Switch

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Section E	TABLE OF CONTENTS	Section E
	- THEORY OF OPERATION SECTION -

Theory of Operation	Section E
Input Power Circuit	E-2
Input Line Voltage	E-2
Main Transformer	E-2
Voltage Selector Switch	E-2
Baffle Mounted Diode Bridge	E-2
Control Circuits	E-3
Output Rectification, Contactor & Control Boards	E-3
Optional Circuits	E-4
Control Board, Gun Trigger, & Wire Drive Motor	E-4
Protective Devices & Circuits	E-5
Thermal Overload Protection	E-5
Wirefeed Overload Protection	E-5

FIGURE E.1 THEORY OF OPERATION BLOCK DIAGRAM

WIRE

GASSPEED

SOLENOIDCONTROL

WIRE

DRIVE

MOTOR

CONTROL BOARD

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LINE

SWITCH

FAN	RECTIFIER
MOTOR	DIODE
	BRIDGE
	28VAC
	TAP SELECTOR
	SWITCH

CONTACTOR

CONTROL

		TACH	TRANSFORMER	OUTPUT BRIDGE
	FEEDBACK	TACH	THERMOSTAT	THERMOSTAT
	FEEDBACK		THERMOSTAT	THERMOSTAT

GUN TRIGGER

OUTPUT DIODE

BRIDGE

++

OUTPUTPOSITIVE

CHOKETERMINAL

GUN

ASSEMBLY

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CONTACTOROUTPUT

CAPACITORS

	RECONNECT	-	-
		MAIN	NEGATIVE
	PANEL	TRANSFORMER
			TERMINAL

POWER MIG 200

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Contents Safety Depends on You Power MIGCalifornia Proposition 65 Warnings SafetyARC Rays can burn Electric Shock can killIii Cylinder may explode if damagedSûreté Pour Soudage a L’Arc Précautions DE SûretéMaster Table of Contents for ALL Sections Installation Section Table of ContentsTechnical Specifications Power MIG Installation3INSTALLATIONA-3 Figure A.1 Dual Voltage Machine Input Connections Figure A.2 Triple Voltage Machine Input Connections Output Polarity ConnectionsCylinder may explode if damaged GUN and Cable InstallationShielding GAS Operation Section B Operation SectionWear eye, ear and body protec- tion OperationWire Size Conversion Parts Wire Drive RollProduct Description Recommended Processes and EquipmentTo Start the Welder Procedure for Changing Drive and Idle Roll SetsWire Reel Loading READI-REELS, Spools or Coils Idle Roll Pressure Setting Feeding Wire Electrode Making a WeldWire Feed Overload Protection Avoiding Wire Feeding ProblemsFAN Control Input Line Voltage VariationsAccessories Section Drive Roll Kits AccessoriesK363P READI-REEL Adapter Dual Cylinder Mounting KIT K1702-1Adapter KIT and Spool GUN InstalledPower MIG Maintenance Section Maintenance Liner Removal and REPLACE- Ment Cause poor wire feedingThis screw should only be gently tightened Overtightening will split or collapse the liner English Metric Description Size GUN Handle DisassemblyMaintenance Power MIG Theory of Operation Section Line SwitchTheory of Operation Motor Control Board Output Rectification Contactor and Control BoardFigure E.4 Optional Circuits Control BOARD, GUN Trigger and Wire Drive MotorThermal and Overload Protection Wirefeed Overload ProtectionPower MIG Troubleshooting and Repair Section F Troubleshooting and Repair SectionHow To Use Troubleshooting Guide Troubleshooting and RepairPC Board Troubleshooting Procedures Perform the Main Transformer Perform the Output Contactor Your body These capacitors is toxicAvoid contact with any portion Function Problems Tachometer Feedback Test Welding Problems Weld bead is narrow or ropy Make sure the welding proce Materials Needed Main Transformer TestTest Description Main Transformer Test ON/OFF Power Switch will be hot during these testsX10 Input Voltage Test Points Table F.1. Test PointsWire Drive Motor and Tachometer Feedback Test Figure F.4. Plug J4 Test ProcedureTest for Supply Voltage to Tachometer Disconnect the main AC input power to the machineVDC Test for Feedback Voltage to Control BoardOutput Bridge Rectifier Test Output Bridge Rectifier Test Test ProcedureContactor Test Figure F.7. Contactor Terminals and Leads Contactor TestTypical Output Voltage Waveform Machine Loaded MAX TAP G Volts 10.0Normal Open Circuit Voltage Waveform MAX TAP G Volts 20.0Machine Loaded to 180 Amps AT 16 VDC Scope Settings Volts 20.0 Description Control Board ReplacementProcedure Control Board ReplacementWire Drive Motor Assembly Replacement Wire Drive Wire Drive Motor Assembly ReplacementBolt Gas Hose TOC Output Diode Bridge Rectifier Replacement Output Diode Bridge Rectifier Mounting Bracket Mounting Bolts Rectifier Power MIG Output Capacitors Replacement Figure F.14. Capacitor Bank Location Output Capacitors ReplacementLead Mounting Bolts Nuts & Lock washers Places Power MIG Main Transformer Replacement 41TROUBLESHOOTING and REPAIRF-41See Figure F.17 Main Transformer ReplacementFigure F.17. Leads X9, X10, 104B,104C, & H1B ReplacementX2 X3 X4 X5 X6 X7 Lead Power MIG FAN BLADE/MOTOR Replacement Perform the Output Capacitor Bank Removal Procedure FAN BLADE/MOTOR ReplacementOutput Contactor Replacement Figure F.24 Output Contactor ReplacementMounting Bolts Retest After Repair Table of Contents Electrical Diagrams Section Electrical DiagramsWiring Diagram Power MIG 200 208/230VSchematic Control PC Board G3851-1 PC Board ASSEMBLY-CONTROLSVM Error Reporting Form