Lincoln Electric SVM170-A 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	SPOOL
						GUN
			SOLENOID	MOTOR			WIRE
							DRIVE
		WIRE					MOTOR
to	to
		SPEED
Return	Return	ARC	CONTROL
		VOLTAGE	BOARD
		AUX					TACH
		115 VAC						GUN TRIGGER
			RECTIFIER
			DIODE	G				FEEDBACK
			BRIDGE
				A
		30 VAC		T
				E
		LINE	SNUBBER	S
			BOARD
		SWITCH		I
				G
				N
TOC				A
	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	the wire drive motor. The drive motor speed is thus
		AND FEEDBACK	controlled which in turn regulates the electrode wire
			feed speed through the gun.
		The wire drive motor is controlled by the control board.	The control board also provides a 3-24 VDC operating
TOC	TOC	A motor speed feedback signal is generated at the	voltage for the optional spool gun. To achieve full WFS
		motor tach and sent to the control board. The control	control at the spool gun, the WFS knob on front of the
SectiontoReturn	MastertoReturn	board compares this feedback signal with the com-	PM-255C must be set at max.
		mands set forth by the Wire Speed Control poten-
		tiometer and sends the appropriate armature voltage to

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