Lincoln Electric SP-250 service manual Figure E.5 Wire Drive Motor and Feedback

E-4 THEORY OF OPERATION E-4

to Section TOC	to Master TOC		POWER SUPPLY OPERATION (CONTINUED)
Return	Return			PIEZO	GAS
			LCD	ALARM	SOLENOID
			DISPLAY				WIRE
							DRIVE
							MOTOR
			KEYPAD	CONTROL BOARD
					G		TACH
					A
					T		GUN TRIGGER AND THUMB SWITCH
		LINE	MAIN		E
					S
			TRANSFORMER
		SWITCH			I		FEEDBACK
					G
					N
TOC	TOC				A
					L
			RECONNECT				POSITIVE
Section	Master
							TERMINAL
						C	CHOKE
						A	F
						P	E
to	to					A	E
						C	D
				SCR		I	B
Return	Return
				RECTIFIER		T	A
						O	C
			FAN			R	K
						S	NEGATIVE
			MOTORS				TERMINAL
							SHUNT

Figure E.5 - Wire Drive Motor and Feedback

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

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