Lincoln Electric SVM157-A service manual Theory of Operation

Page 30

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E-2	THEORY OF OPERATION	E-2
	FIGURE E.2 – INPUT POWER CIRCUIT.

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LINE

SWITCH

			WIRE
	GAS		SPEED
	SOLENOID		CONTROL
			WIRE
			DRIVE
			MOTOR
	CONTROL BOARD
FAN	RECTIFIER
MOTOR	DIODE			TRANSFORMER	OUTPUT BRIDGE
	BRIDGE		TACH	TRANSFORMER	OUTPUT BRIDGE
			TACH	THERMOSTAT	THERMOSTAT
	28VAC	CONTACTOR CONTROL	FEEDBACK	THERMOSTAT	THERMOSTAT
	28VAC	CONTACTOR CONTROL	GUN TRIGGER
	TAP SELECTOR		GUN TRIGGER
	TAP SELECTOR
	SWITCH
			OUTPUT DIODE
			BRIDGE
			+	+
			OUTPUT	POSITIVE
			CHOKE	POSITIVE
			CHOKE	TERMINAL
				TERMINAL
		CONTACTOR	OUTPUT
			CAPACITORS
RECONNECT			-	-
RECONNECT	MAIN			NEGATIVE
PANEL	TRANSFORMER			NEGATIVE
PANEL	TRANSFORMER			TERMINAL
				TERMINAL

GUN

ASSEMBLY

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	INPUT LINE VOLTAGE, MAIN	from a minimum setting (A) to a maximum
	TRANSFORMER, VOLTAGE	voltage setting (G). In addition, the main
	TRANSFORMER, VOLTAGE	transformer houses a 28VAC winding. This
	SELECTOR SWITCH AND	transformer houses a 28VAC winding. This
	SELECTOR SWITCH AND	28VAC is rectified at the baffle mounted diode
	BAFFLE MOUNTED DIODE	bridge and the resultant DC voltage is used to
	BRIDGE	power the electronics on the control board, the
	BRIDGE	output contactor, and the gas solenoid.
		output contactor, and the gas solenoid.
	The single phase input power is connected to
	the POWER MIG 200 through a line switch
	located on the front panel.
	A reconnect panel allows the user to configure
	the machine for the desired input voltage. The
	AC input voltage is applied to the primary of the
	main transformer. The cooling fan motor
	(120VAC) is powered from a portion of the
	primary winding. For welding purposes, the
	main transformer converts the high voltage, low
	current input power to a lower voltage, higher
	current output. This tapped secondary winding
	is coupled to a voltage selector switch. By
	selecting one of seven positions on the switch
	the user can preset the desired voltage output

NOTE: Unshaded areas of block logic diagrams are the subject of discussion.

POWER MIG 200

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Contents Power MIG Safety Depends on YouSafety California Proposition 65 WarningsElectric Shock can kill ARC Rays can burnCylinder may explode if damaged IiiPrécautions DE Sûreté Sûreté Pour Soudage a L’ArcMaster Table of Contents for ALL Sections Table of Contents Installation SectionInstallation Technical Specifications Power MIG3INSTALLATIONA-3 Figure A.1 Dual Voltage Machine Input Connections Output Polarity Connections Figure A.2 Triple Voltage Machine Input ConnectionsGUN and Cable Installation Shielding GASCylinder may explode if damaged Operation Section Operation Section BOperation Wear eye, ear and body protec- tionProduct Description Wire Drive RollWire Size Conversion Parts Recommended Processes and EquipmentProcedure for Changing Drive and Idle Roll Sets Wire Reel Loading READI-REELS, Spools or CoilsTo Start the Welder Feeding Wire Electrode Making a Weld Idle Roll Pressure SettingFAN Control Avoiding Wire Feeding ProblemsWire Feed Overload Protection Input Line Voltage VariationsAccessories Section K363P READI-REEL Adapter AccessoriesDrive Roll Kits Dual Cylinder Mounting KIT K1702-1Installed Adapter KIT and Spool GUNPower MIG Maintenance Section Maintenance This screw should only be gently tightened Cause poor wire feedingLiner Removal and REPLACE- Ment Overtightening will split or collapse the linerGUN Handle Disassembly English Metric Description SizeMaintenance Power MIG Line Switch Theory of Operation SectionTheory of Operation Output Rectification Contactor and Control Board Motor Control BoardControl BOARD, GUN Trigger and Wire Drive Motor Figure E.4 Optional CircuitsWirefeed Overload Protection Thermal and Overload ProtectionPower MIG Troubleshooting and Repair Section Troubleshooting and Repair Section FTroubleshooting and Repair How To Use Troubleshooting GuidePC Board Troubleshooting Procedures Perform the Main Transformer Perform the Output Contactor These capacitors is toxic Avoid contact with any portionYour body Function Problems Tachometer Feedback Test Welding Problems Weld bead is narrow or ropy Make sure the welding proce Main Transformer Test Test DescriptionMaterials Needed ON/OFF Power Switch will be hot during these tests Main Transformer TestX10 Table F.1. Test Points Input Voltage Test PointsWire Drive Motor and Tachometer Feedback Test Test Procedure Figure F.4. Plug J4Disconnect the main AC input power to the machine Test for Supply Voltage to TachometerTest for Feedback Voltage to Control Board VDCOutput Bridge Rectifier Test Test Procedure Output Bridge Rectifier TestContactor Test Contactor Test Figure F.7. Contactor Terminals and LeadsVolts 10.0 Typical Output Voltage Waveform Machine Loaded MAX TAP GVolts 20.0 Normal Open Circuit Voltage Waveform MAX TAP GMachine Loaded to 180 Amps AT 16 VDC Scope Settings Volts 20.0 Control Board Replacement DescriptionControl Board Replacement ProcedureWire Drive Motor Assembly Replacement Wire Drive Motor Assembly Replacement Wire DriveBolt Gas Hose TOC Output Diode Bridge Rectifier Replacement Output Diode Bridge Rectifier Mounting Bracket Mounting Bolts Rectifier Power MIG Output Capacitors Replacement Output Capacitors Replacement Figure F.14. Capacitor Bank LocationLead Mounting Bolts Nuts & Lock washers Places Power MIG 41TROUBLESHOOTING and REPAIRF-41 Main Transformer ReplacementMain Transformer Replacement See Figure F.17Replacement Figure F.17. Leads X9, X10, 104B,104C, & H1BX2 X3 X4 X5 X6 X7 Lead Power MIG FAN BLADE/MOTOR Replacement FAN BLADE/MOTOR Replacement Perform the Output Capacitor Bank Removal ProcedureOutput Contactor Replacement Output Contactor Replacement Figure F.24Mounting Bolts Retest After Repair Electrical Diagrams Table of Contents Electrical Diagrams SectionPower MIG 200 208/230V Wiring DiagramSchematic Control PC Board PC Board ASSEMBLY-CONTROL G3851-1SVM Error Reporting Form