Lincoln Electric IM491-B manual Symptom Check

SYMPTOM		CHECK
No LED’s light when the power switch is turned on.	1.	Check the input power to be sure it is on.
	2.	Check the power line fuses and machine
		connection.
	3.	Replace line switch.
The “MACHINE ON” LED is lit, but there is no	1.	Check the “SAFETY” LED. If it is lit, check the
response when the trigger is pulled.		torch consumables and press the “SAFETY
		RESET” button.
	2.	Check the air supply to the machine. If the air
		does not flow, the machine will not start.
	3.	Check the operation of the air solenoid by
		switching the machine to “PURGE”. If the
		pressure is sufficient, the air should begin to
		flow and the “AIR PRESSURE” LED should
		turn on. Return to “RUN” mode. If air does not
		flow, check the solenoid by applying 115 VAC to
		its input leads. If it is not bad, replace PC board.
	4.	Low air pressure also results in a “no start”
		condition. “AIR PRESSURE” LED must be lit
		when air is flowing.
	5.	12 seconds, or more, of postflow time has
		elapsed and a double trigger pull is required to
		start the pilot arc. The second trigger pull must
		follow the first within 1 second to start the pilot
		arc.

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