Lincoln Electric SVM 119-A service manual Leads

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F-17 TROUBLESHOOTING & REPAIR F-17

ACTIVE SCR RECTIFIER ASSEMBLY TEST (CONTINUED)

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TEST PROCEDURE

1.Disconnect main AC input power to the machine.

2.Disconnect Molex Plugs J3 and J6 from the G2803 Control Board. See Figure F.5.

		J3
255 CONTROL G2803
WM-		J9
		J6
		J4
		J5
J1	J7	J10
		J2

FIGURE F.5 - Control Board Molex Plug Locations for G2803 PC Control Board.

3.Verify that the capacitors have com- pletely discharged with an Analog Volt-Ohm meter.

4.Disconnect leads X2 and X3 from the negative capacitor bank using a 1/2" open end wrench.

See Figure F. 6.

LEADS

X2 AND X3

NEGATIVE

CAPACITOR

BANK

BUSS BAR

FIGURE F.6 - Location of Leads X2

and X3.

5.Separate leads X2 and X3 from the negative capacitor bank buss bar. Be sure there is no electrical con- tact. See Figure F.6.

NOTE: DO NOT DISASSEMBLE THE

SCR RECTIFIER HEAT SINK ASSEM-

BLY.

6.Construct the circuit shown in Figure F.7. One 6-volt lantern battery can be used. R1 and R2 resistor values are ±10%. Set voltmeter scale low, at approximately 0-5 volts or 5-10 volts.

a.Test the voltage level of the bat- tery. Short leads (A) and (C). Close switch SW-1. Battery voltage should be 4.5 volts or higher. If lower, replace the bat- tery.

WIRE-MATIC 255