Lincoln Electric SVM169-A service manual High Voltage / High Frequency Circuit

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E-4		THEORY OF OPERATION				E-4
	FIGURE E.4 High Voltage/High Frequency Circuit.
						BY-PASS
						BOARD
			POLARITY
			SWITCH
		MAIN				HI-FREQUENCY
		TRANSFORMER				TRANSFORMER
	INPUT
	POWER
	SWITCH BYPASS					C
	ASBLY
						H
		H1
			AC	DC+		O
		X1
						K
			SCR
			BRIDGE			E
		H2			SHUNT	HIGH VOLTAGE
		X2
			AC	DC-		TRANSFORMER
		H3
					F	CIRCUIT
					E
					E
					D
					B
					A
					C
					K
		18VAC				115VAC
		18VAC		CONTROL		POWER
	FAN	115VAC		BOARD		"ON"
						DIGITAL
						DISPLAY
						MODE
						SWITCH
		REMOTE
		RECEPTACLE	THERMAL	GAS	THERMO-	OUTPUT
					STATS
			LIGHT	VALVE		CONTROL

HIGH VOLTAGE / HIGH

FREQUENCY CIRCUIT

The control board passes the 115VAC voltage to the primary of the high voltage transformer. The sec- ondary of the high voltage transformer is coupled to a spark gap generator and also to the high frequency transformer. The high frequency transformer transfers the high frequency “spark” to the electrode terminal which is coupled to the TIG torch.

NOTE: Unshaded areas of block logic diagrams are the subject of discussion.

PRECISION TIG 185