Lincoln Electric SVM 117-A service manual Figure E.4 Constant Voltage Output

E-3 THEORY OF OPERATION E-3

to Section TOC	to Master TOC		CONSTANT VOLTAGE OUTPUT
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.4 - Constant Voltage Output.

TOC	TOC	CONSTANT VOLTAGE OUTPUT
Section	Master
		The controlled DC output from the SCR rectifier
to	to	assembly is filtered by the capacitor bank resulting is a
		constant voltage DC output. Since the output choke is
Return	Return
		in series with the positive leg of the rectifier and also in
		series with the gun and welding load, a filtered con-
		stant voltage output is applied to the output terminals
		of the machine.

Section TOC	Master TOC
to	to	NOTE: Unshaded areas of Block Logic
		Diagram are the subject of discussion
Return	Return
		WIRE-MATIC 250