Lincoln Electric IM491-B manual Check to see that the torch is hooked to

SYMPTOM		CHECK
The “SAFETY” LED is lit.	1.	The machine will not operate. The machine
		senses that the shield cup is not in place, or the
		operators could be exposed to dangerous
		voltages if the machine were allowed to operate.
	2.	Check the shield cup to be sure it is tightly in place.
	3.	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”.
	4.	Check the torch cable to see if it is cut or
		punctured. Replace.
	5.	Check to see that the torch is hooked to the
		machine properly.
	6.	Push the ‘SAFETY RESET” button, the LED
		should go out.
	7.	This circuit rarely trips on power up or because
		of noise. If the circuit can be reset, it is OK to
		continue operation.
	8.	Replace Control PC board, as this is a
		safety problem.
The “OUTPUT ON” and “MALFUNCTION” LED’s	1.	The pilot arc duty cycle has been exceeded.
blink in alternating order.		The machine will cool down and the lights will
		quit blinking in about 10 seconds. The pilot arc
		is limited to 20 out of 80 seconds except in
		special circumstances such as cutting
		expanded metal. (See the section on expanded
		metal in the Operating Section.)
Airflow will not shut off.	1.	Check harness 1J7 (332) and 3J7 (333) 24VAC
		auxiliary supply.
	2.	Replace Control PC board.
No OCV when 2 and 4 are closed.	1.	Check CR1.
	2.	230 VAC across CR1.
	3.	250V SCR PC board positive/negative
	4.	Check across 31/32 for 110 VAC.
	5.	Replace Control PC board.

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