Lincoln Electric SVM140-A service manual LOW Voltage Circuit Test, Return Section TOC

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F-45 F-45

TROUBLESHOOTING & REPAIR

LOW VOLTAGE CIRCUIT TEST (continued)

FIGURE F.12 - LOW VOLTAGE CIRCUIT DIAGRAM

T2 AUXILIARY

TRANSFORMER

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TO H1

"C" TERMINALH1 INPUT

RECTIFIER

H2

H3

TO

RECONNECT

LEAD "A"

H4

H5

	BROWN	8	#53	3J30
12VAC BROWN		3	#56	=17VDC
				6J30		PLASMA
						OUTPUT
	RED	2	#51	1J30		BOARD
24VAC	RED	6	#54	=28VDC
				4J30
	BLUE		#61							D
		4		1J1			#216
						6J2			15J40	I	B
18VAC				=+15VDC
	WHITE							+
			#62							S	O
		5		2J1	CONTROL BOARD			+15VDC
										P	A
18VAC	BLUE		#64	=-15VDC		9J2	#219		10J40
		9		4J1
										L	R
										A	D
										Y
		J21

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PROCEDURE

1.Remove input power to the Pro-Cut 55 machine.

2.Using the 5/16" nutdriver remove the case wraparound cover.

WARNING

ELECTRIC SHOCK can kill.

• Do not touch electrically hot parts.

3.Apply the correct input power to the machine and carefully check for the following voltages.

4.Check for the presence of approximately 28 VDC on the output board.

a.LED1 should be lit when 28 VDC is present. See Figure F.13. See Output Board LED Definitions and Figure F.12, Low Voltage Circuit Diagram.

b.To verify the presence of 28 VDC, check across capacitor C13. Make certain the voltmeter probes make good contact with the capacitor leads. See Figure F.13.

5.Check for the presence of 17 VDC on the out- put board.

a.LED2 should be lit when 17 VDC is present. See Figure F.13. See Output Board LED Definitions and Figure F.12, Low Voltage Circuit Diagram.

b.To verify the presence of 17 VDC, check from plug J31 Pin-6 to diode D25 (anode). See Figure F.13. Make certain the volt- meter probes make good contact with pin- 6 and the diode anode lead.

6.Check for the presence of +15 VDC on the control board.

a.LED1 should be lit when +15 VDC is pre- sent. See Figure F.13. See Control Board LED Definitions and Figure F.12, Low Voltage Circuit Diagram.

7.Check for the presence of -15 VDC on the con- trol board.

a.LED3 should be lit when -15 VDC is pre- sent. See Figure F.13. See Control Board LED Definitions and Figure F.12, Low Voltage Circuit Diagram.

PRO-CUT 55