Lincoln Electric SVM 117-A service manual Input Line Voltage and Main, Transformer

E-1 THEORY OF OPERATION E-1

to Section TOC	to Master TOC		INPUT LINE VOLTAGE AND MAIN TRANSFORMER
Return	Return		WIRE	GAS
			SPEED	SOLENOID
							WIRE
							DRIVE
			ARC				MOTOR
			VOLTAGE
			CONTROL BOARD
				G			TACH
				A
				T		GUN TRIGGER AND THUMB SWITCH
		LINE	MAIN	E
				S
			TRANSFORMER
		SWITCH		I			FEEDBACK
				G
				N
TOC				A
	TOC			L
			RECONNECT				POSITIVE
Section	Master
							TERMINAL
					C		CHOKE
					A	F
					P	E
					A	E
to	to
					C	D
			SCR		I	B
Return	Return		RECTIFIER		T	A
					O	C
			FAN		R	K	NEGATIVE
					S
			MOTORS				TERMINAL
						SHUNT

Figure E.2 - Input Line Voltage and Main Transformer.

TOC	TOC	INPUT LINE VOLTAGE AND MAIN
Section	Master	TRANSFORMER
		The desired single phase input power is connected to
to	to	the WIRE-MATIC 250 through a line switch located on
Return	Return	A reconnect panel allows the user to configure the
		the front panel.
		machine for the desired input voltage. This AC input
		voltage is applied to the primary of the main trans-
		former and to the thermostatically controlled fan
		motors. The transformer changes the high voltage, low
		current input power to a low voltage, high current out-
		put. In addition, the main transformer also has an iso-
		lated center tapped 30 VAC auxiliary winding that sup-
TOC	TOC	plies power to the Control Board for SCR gate drive
		and gas solenoid operation. The weld power windings
Section	Master	connect to the Control Board as well as to the main
		SCR Rectifier.
to	to		NOTE: Unshaded areas of Block Logic
			Diagram are the subject of discussion
Return	Return
			WIRE-MATIC 250