Lincoln Electric SVM144-B service manual Wire Drive Motor, Feedback

E-5 THEORY OF OPERATION E-5

TOC	TOC	FIGURE E.5 — WIRE DRIVE MOTOR AND FEEDBACK.
Section	Master		GAS	FAN
			SOLENOID	MOTOR		WIRE
						DRIVE
		WIRE				MOTOR
to	to
		SPEED
Return	Return	ARC	CONTROL
		VOLTAGE	BOARD
						TACH
		115 VAC					GUN TRIGGER
			RECTIFIER
			DIODE	G			FEEDBACK
			BRIDGE
				A
		30 VAC		T
				E
		LINE	SNUBBER	S
			BOARD
		SWITCH		I
				G
				N
				A
TOC	TOC			L
Section	Master			POWER	C	F	OUTPUT	POSITIVE
		RECONNECT		ENHANCEMENT	A		CHOKE
								TERMINAL
		MAIN		CHOKE	P	E
		TRANSFORMER			A	E
			SCR		C	D
to	to					B
			RECTIFIER		I
					T	A
Return	Return
					O	C		NEGATIVE
					R	K
								TERMINAL
					S
					SHUNT

		WIRE DRIVE MOTOR	board compares this feedback signal with the com-
		AND FEEDBACK	mands set forth by the Wire Speed Control poten-
			tiometer and sends the appropriate armature voltage to
		The wire drive motor is controlled by the control board.	the wire drive motor. The drive motor speed is thus
			controlled which in turn regulates the electrode wire
Return to Section TOC	Return to Master TOC	A motor speed feedback signal is generated at the	feed speed through the gun.
		motor tach and sent to the control board. The control

Section TOC	Master TOC
to	to	NOTE: Unshaded areas of Block Logic
		Diagram are the subject of discussion
Return	Return
		POWER MIG 255