Lincoln Electric SVM162-B service manual Figure E.7 AC Welding Output

REMOTE

RECEPTACLE

electrically across the negative and positive SCR bridge connections. With the ability of the choke to store energy and the SCRs to turn on at the appropri- ate times, an AC square wave is developed and applied to the output terminals. The bypass board pro- tects the internal circuitry from interference.

ADVANCED CONTROL PANEL RECEPTACLE

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E-6 THEORY OF OPERATION E-6

FIGURE E.7 – AC WELDING OUTPUT

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FROM

CONTROL

BOARD

OPTIONAL POWER

CORRECTIONFACTOR

CAPACITORS

POWER

SWITCH

PANEL

RECONNECT

BACKGROUND

CIRCUIT

63.5 VAC

			REAR GANG		WORK
		POLARITY
		SWITCH	BYPASS	BOARD
					FRONT
				HIGH FREQUENCY	ELECTRODE
X1
				TRANSFORMER	REAR
78 VAC			CHOKE		ELECTRODE
	AC	DC
X2
	SCR			HIGH VOLTAGE
				TRANSFORMER
	BRIDGE
	AC	DC	SHUNT

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115 VAC THERMOSTAT

115 VAC VAC115

20 VAC

20 VAC

LEADSGATE	FEEDBACK	GAS
		VAC
FAN		SOLENOID
		115

CONTROL BOARD

115 VAC

THERMOSTAT

LED's

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MINIMUM
OUTPUT	PROTECTION	METER	STICK
CONTROL
	BOARD		TIG
			SWITCH	BALANCE	POST	LOCAL/REMOTE
				CONTROL	FLOW	SWITCH

MAXIMUM

OUTPUT

CONTROL

AC WELDING OUTPUT

Rotating the polarity switch to the AC position changes the welding power circuit. One lead (X1) of the main transformer secondary is connected to the machineʼs output work terminal. The other secondary lead (X2) is connected to one of the AC connections of the SCR bridge. The electrode terminal is connected to the other AC side of the bridge. The choke is now

FIGURE E.8 DC WELDING CURRENT GENERATION

G	CHOKE	G	ELECTRODE
G			G

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PRIMARY 10

DC

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WORK

PRECISION TIG 275