Theory of Operation | Lincoln Electric SVM157-A manual

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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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Lincoln Electric SVM157-A service manual Theory of Operation

Contents

Power MIG Safety Depends on You Safety California Proposition 65 Warnings Electric Shock can kill ARC Rays can burn Cylinder may explode if damaged Iii Précautions DE Sûreté Sûreté Pour Soudage a L’Arc Master Table of Contents for ALL Sections Table of Contents Installation Section Installation Technical Specifications Power MIG 3INSTALLATIONA-3 Figure A.1 Dual Voltage Machine Input Connections Output Polarity Connections Figure A.2 Triple Voltage Machine Input Connections GUN and Cable Installation Shielding GASCylinder may explode if damaged Operation Section Operation Section B Operation Wear eye, ear and body protec- tion Product Description Wire Drive RollWire Size Conversion Parts Recommended Processes and Equipment Procedure 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 Setting FAN Control Avoiding Wire Feeding ProblemsWire Feed Overload Protection Input Line Voltage Variations Accessories Section K363P READI-REEL Adapter AccessoriesDrive Roll Kits Dual Cylinder Mounting KIT K1702-1 Installed Adapter KIT and Spool GUN Power 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 liner GUN Handle Disassembly English Metric Description Size Maintenance Power MIG Line Switch Theory of Operation Section Theory of Operation Output Rectification Contactor and Control Board Motor Control Board Control BOARD, GUN Trigger and Wire Drive Motor Figure E.4 Optional Circuits Wirefeed Overload Protection Thermal and Overload Protection Power MIG Troubleshooting and Repair Section Troubleshooting and Repair Section F Troubleshooting and Repair How To Use Troubleshooting Guide PC 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 Test X10 Table F.1. Test Points Input Voltage Test Points Wire Drive Motor and Tachometer Feedback Test Test Procedure Figure F.4. Plug J4 Disconnect the main AC input power to the machine Test for Supply Voltage to Tachometer Test for Feedback Voltage to Control Board VDC Output Bridge Rectifier Test Test Procedure Output Bridge Rectifier Test Contactor Test Contactor Test Figure F.7. Contactor Terminals and Leads Volts 10.0 Typical Output Voltage Waveform Machine Loaded MAX TAP G Volts 20.0 Normal Open Circuit Voltage Waveform MAX TAP G Machine Loaded to 180 Amps AT 16 VDC Scope Settings Volts 20.0 Control Board Replacement Description Control Board Replacement Procedure Wire Drive Motor Assembly Replacement Wire Drive Motor Assembly Replacement Wire Drive Bolt 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 Location Lead Mounting Bolts Nuts & Lock washers Places Power MIG 41TROUBLESHOOTING and REPAIRF-41 Main Transformer Replacement Main Transformer Replacement See Figure F.17 Replacement Figure F.17. Leads X9, X10, 104B,104C, & H1B X2 X3 X4 X5 X6 X7 Lead Power MIG FAN BLADE/MOTOR Replacement FAN BLADE/MOTOR Replacement Perform the Output Capacitor Bank Removal Procedure Output Contactor Replacement Output Contactor Replacement Figure F.24 Mounting Bolts Retest After Repair Electrical Diagrams Table of Contents Electrical Diagrams Section Power MIG 200 208/230V Wiring Diagram Schematic Control PC Board PC Board ASSEMBLY-CONTROL G3851-1 SVM Error Reporting Form