Lincoln Electric SVM170-A service manual Table of Contents Theory of Operation Section

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SECTION E	THEORY OF OPERATION	SECTION E
	TABLE OF CONTENTS
	-THEORY OF OPERATION SECTION-
Theory of Operation	. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . Section E
Input Line Voltage and Main Transformer		. . . E-2
Output Rectification and Feedback Control		. . . E-3
Constant Voltage Output	. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . E-4
Wire Drive Motor and Feedback		. . . E-5
Thermal and Overload Protection		. . . E-6
Overcurrent Protection		. . . E-6
Wire Feed Overload Protection		. . . E-6
SCR Operation	. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . E-7

FIGURE E.1 — BLOCK LOGIC DIAGRAM.

	GAS	FAN	SPOOL
	SOLENOID	MOTOR		GUN	WIRE
					DRIVE
WIRE					MOTOR
SPEED
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
		A
		L
		POWER		C	F	OUTPUT	POSITIVE
RECONNECT		ENHANCEMENT		A		CHOKE
							TERMINAL
MAIN		CHOKE		P	E
TRANSFORMER				A	E
	SCR			C	D
	RECTIFIER			I	B
				T	A
				O	C		NEGATIVE
				R	K
							TERMINAL

S

SHUNT

NOTE: Unshaded areas of Block Logic

Diagram are the subject of discussion

POWER MIG 255C