Lincoln Electric IM491-B manual Symptom Check

SYMPTOM		CHECK
The “MALFUNCTION” LED is lit.	1.	The FAULT circuit monitors the torch to see if it is
		shorted as well as internal machine failures.
	2.	Check the torch consumables to see if they are
		melted together or are simply touching each
		other. Tighten, clean or replace. See
		“Suggestions for Extra Utility from the PRO-CUT
		System”.
	3.	Check the torch cable to see if it is cut or
		punctured. Replace.
	4.	Turn off the machine and turn it back on. If the
		“FAULT” LED will not stay off when you
		try to cut again and there is no problem with the
		torch, then something has failed in the machine
		and the machine should not be left on.
		4a. Check electrode to pilot for short.
		4b. Check the SCR board. Replace if bad.
		4c. Check operation of contactors. Replace if bad.
	5.	Replace Control PC board.
Alternating “AIR/MALFUNCTION” LED lights	1.	Replace Control PC board.
Air pressure cannot be set to 60 psi (414 kPa) or the	1.	Watch the pressure gauge during pilot mode.
machine cuts poorly through thick sections.		The air pressure should start as 60 psi (414 kPa)
		and be reduced significantly when the trigger is
		pulled. If not, then there is a problem with the
		solenoid assembly.

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