Lincoln Electric SVM127-A service manual Table of Contents Theory of Operation Section

	Section E-1		Section E-1
TOC		TABLE OF CONTENTS
		-THEORY OF OPERATION SECTION-
to Master	Theory of Operation		Section E
		General Description	E-2
Return		Power Input Circuits	E-2
		Trigger and Shutdown Circuit	E-3
		Arc Voltage, Wire Speed Control and Metering	E-4
		Printed Circuit Board Functions	E-5

TOC
Master										VOLTAGE CONTROL
								WORK VOLTAGE SENSING
to
						GEAR		ELECTRODE VOLTAGE SENSING		POLARITY
Return
						BOX				SWITCH
										WIRE
						WIRE				SPEED
										CONTROL
						FEED
						MOTOR	TACH
							BOARD
		POWER SOURCE OUTPUT TRIGGER			(#2 )
								WIRE SPEED CONTROL
				TRIGGER		T2		+ 15VDC
		CIRCUIT	TRIGGER	BOARD
			CONNECTOR						C
		BREAKER			24VAC
									O	B
								TRIGGER SIGNAL
	INPUT								N	O
						F
						U			T	A
	CONNECTOR					S				R
						E			R
		R1						+ 15VDC		D
TOC						P	B		O
						O
							O		L
						W	A
								S
						E	R
								H
Master						R	D	U
								T
	TO							D
								O
	CONTROL							W
	BOARD							N
		T1						R	V
to
								E	O
								F
	TO								L
								E
Return									T
	VOLTAGE							R
								E	A
	BOARD							N	G
								C	E
	METER							E
		10VAC	28VAC
	BOARD
						WIRE FEED				VOLTAGE
										CONTROL
						MOTOR
	VOLTS					THERMOSTAT
	SPEED
	SWITCH								VOLTAGE
									BOARD

TRIGGER SIGNAL

TOC
		LEAD
		GROUND
MastertoReturn		PROTECTOR
	FIGURE E.1 – LN-9 BLOCK LOGIC DIAGRAM
	LN-9 Wire Feeder