Lincoln Electric R3R-500, R3R-300 service manual Active SCR Test

		F-29			F-29
		TROUBLESHOOTING & REPAIR
TOC	TOC	ACTIVE SCR TEST (continued)
Section	Master
		P1 AND P3 LOCATIONS	G1575 LEAD LOCATIONS
		FIGURE F.16 – CONTROL BOARD PLUG	FIGURE F.17 – CONTROL BOARD
to	to
				R3R CONTROL
Return	Return		G1
				G2	G3
				G1575 - [	]

TOC	TOC		Plug P3
		R3R CONTROL
Section	Master
		G2206 - [	]
to	to	Plug P4 (Removed)
Return	Return	FIGURE F.18 – SNUBBER BOARD PLUG		FIGURE F.19 – RESISTOR R3 LOCATION
		P5 LOCATION
			Plug P5
				RESISTOR R3
Section TOC	Master TOC	M15370-[ ] SNUBBER
Return to	Return to
		TEST PROCEDURE

		1.	Disconnect the main input supply power to	5.	Locate and remove molex plug P5 from
			the machine.		snubber board M15370. See Figure F.18. If
		2.	With the 5/16” nut driver, remove the case		the machine has snubber board M14215, it
					will be necessary to label and disconnect
			top and sides. Remove the screws holding
					lead #204 from the output shunt. Be sure to
			the front panel and lower the panel.
					disconnect the #204 lead that runs
TOC	TOC	3.	Disconnect the welding cables from the		between the snubber board and the out-
			welding output terminals.		put shunt.
Section	Master	4.	Locate and remove molex plug P4 from con-	6.	Locate and remove lead #204 from resistor
			If the machine has control board G1575, dis-		R3 (40 ohms, 50 Watts). See Figure F.19.
			trol board G2206. See Figure F.16.
to	to		connect the individual gate leads G1, G2,
Return	Return		and G3 and also lead #204. See Figure F.17.
			IDEALARC R3R