Lincoln Electric SVM 117-A service manual Figure F.7 SCR Tester Circuit, SCR connections

		F-18	TROUBLESHOOTING & REPAIR		F-18
TOC	TOC		ACTIVE SCR RECTIFIER ASSEMBLY TEST (CONTINUED)
Section	Master		7. Connect the Tester to the SCR 1 as	10. Close or keep closed switch SW-1.
			shown in Figure F.7.
to	to		a. Connect Tester lead (A) to the	11. Close switch SW-2 for 2 seconds
				and release and read meter.
Return	Return
			anode.
			b. Connect Tester lead (C) to the	a. If the voltage is 3 - 6 volts while
				the switch is closed and after
			cathode.	the switch is open, the SCR is
				functioning.

c.Connect Tester lead (G) to the

	gate.	b.	If the voltages is 3-6 volts only
			when the switch is closed or
			there is no voltage when the
TOC	TOC		switch is	closed, the SCR is
			defective.
Section	Master
		results of the test.		Repeat Battery Test
		NOTE: Be sure battery is functioning
		properly. A low battery can affect the
to	to	Procedure in Step 6 if needed.
Return	Return	12. Open switch SW-1.
		13. Reconnect the Tester leads. See
		Figure F.7.
		a.	Connect Tester lead (A) to the
			cathode.
		b.	Connect Tester lead (C) to the
TOC	TOC		anode.
		c.	Disconnect Test lead (G) from
Section	Master
			the gate.
to	to	14. Close switch SW-1.
Return	Return	15. Read meter for zero voltage.
		a.	If the voltage is zero, the SCR is
			functioning.
	FIGURE F.7 - SCR Tester Circuit and	b.	If the voltage is higher than
			zero, the SCR is shorted.
	SCR connections.

TOC	TOC	8.	Close switch SW-1.	16.	Perform the Active Test Procedure
		NOTE: Switch SW-2 should be open.			outlined in Steps 5-13for SCR 2.
				18.	Replace all Molex Plugs onto the
Sectionto	Masterto		a. If the voltage reading is higher
		9.	Read meter for zero voltage.	17.	Replace all SCR assemblies that do
Return	Return				not pass the above tests.
			than zero, the SCR is shorted.		Control Board and connect leads X2
					and X3.
			WIRE-MATIC 250