Lincoln Electric SVM104-A service manual Output Rectification Control and Feedback

					THEORY OF OPERATION			E-2
Return to Section TOC	Return to Master TOC		FIGURE E.3 - Output Rectification, Control and Feedback
Return to Section TOC	Return to Master TOC
Section TOC	Master TOC	OUTPUT RECTIFICATION,
to	to
		CONTROL AND FEEDBACK
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		The AC output from the main transformer sec-					into an isolated drive signal. This isolated signal
		ondary is rectified through the SCR/ DIODE					drives the transistor module to the optimum level
		bridge. The machine output is controlled through					to obtain the desired machine output current. The
		the	transistor module.	The	output current is		control and power board also generate the gate
		sensed at the shunt, as a low voltage signal, and					firing pulses for the SCR/DIODE bridge. The rec-
		fed back to the control board.			The control board		tified and controlled DC voltage is filtered by the
		compares the commands of the output control					output capacitors and choke and is applied to the
TOC	TOC	potentiometer with the shunt feedback signal and					machine's torch and work terminals. The control
		the appropriate pulse width modulated (PWM)					board also operates the status board and com-
		control signal is sent to the power board.				The	mands the pilot arc circuitry.
to Section	to Master
		power board converts the PWM control signal
					NOTE: Unshaded areas of Block Logic
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					Diagram are the subject of discussion

PRO-CUT 60