Lincoln Electric SVM101-B service manual Theory of Operation Section, Section E-1

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Section E-1	TABLE OF CONTENTS	Section E-1
	- THEORY OF OPERATION SECTION -

Theory of Operation	Section E
Power Supply Operation	E-2
Pre Charge and Protection Circuitry	E-3
Switch Board and Main Transformer	E-4
Control and Output Circuitry	E-5
Field Effect Transistor (FET) Operation	E-6
Pulse Width Modulation	E-7
Protective Circuits	E-8

FIGURE E.1 – V300-I BLOCK LOGIC DIAGRAM

					POWER SWITCH
					SECTIONS			MAIN		RECTIFIER
					20KHZ				CHOKE
								TRANSFORMER
										HEATSINK
				LEFT SWITCH BOARD
					FET MODULES			TOP
					CAP
										1 DIODE
					FET MODULES		CURRENT
		1ø OR 3ø DETETCTION (H5)
							TRANSFORMER
			PRE-CHARGE
	LINE	INPUT	DRIVER
	SWITCH	RECTIFIER	BOARD				CONTROL			5 DIODES
			CR1
1							BOARD
		AC1		PROTECTION
			PULSE
2		AC2		BOARD			Y-Y FEEDBACK	BOTTOM
			TRAIN
3		AC3
	3A		CR2
		A-LEAD
		24VDC	PRE-CHARGE
FAN	AUXILIARY			RIGHT SWITCH BOARD
										5 DIODES
	TRANSFORMER		2ND STEP PWM
		18VAC			FET MODULES
		24VAC	POWERBOARD		CAP
								TOP
					FET MODULES
			<1 VDC							1 DIODE
	TO								CHOKE		CHOKE
	WIREFEEDER
			LOCAL	METER	MODE	POT	POT	VOLTAGE FEEDBACK
			REMOTE
			1ST STEP PWM VOLTAGE					CURRENT FEEDBACK-PROTECTION			SHUNT
			15VDC-CONTROL BOARD FUNCTION VOLTAGE
			24VAC-THERMOSTATS-GUN TRIGGERING

V300-I