Lincoln Electric DC-655 service manual Output, LED Chart, Perform the SCR Bridge Test

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F-6		F-6
	TROUBLESHOOTING & REPAIR
	TROUBLESHOOTING GUIDE	Observe Safety Guidelines
		detailed in the beginning of this manual.

PROBLEMS	POSSIBLE AREAS OF				RECOMMENDED
(SYMPTOMS)	MISADJUSTMENT(S)				COURSE OF ACTION
	OUTPUT PROBLEMS
The machine has welding output	1. Check the output control switch				1.	The output control potentiome-
but no control.	(SW3) for proper setting.					ter, output control switch (SW3)
	2. If a	remote	control	cable is		or associated		wiring	may be
						defective.	See the Wiring
	used,	make	certain	the cable
						Diagram.
	and connections are good.
					2. Perform the Firing Board Test.
					3.	Perform the		SCR	Output
						Bridge Test.
					4. The control			board	may be
						faulty. See the Control Board
						LED Chart.
The machine does not have maxi-	1. Check the three-phase input				1.	The output control potentiome-
mum output.	lines at the DC-655.			Make cer-		ter, output control switch (SW3)
	tain the input voltages match					or associated wiring may be
	the machine’s rating and recon-					defective.	See the Wiring
	nect panel configuration.					Diagram.
	2. Put the output control switch				2.	Perform the Main Transformer
	(SW3) in the “Local” control					Test.
	position. If		the problem is		3. Perform the Firing Board Test.
	resolved, the remote unit or
	wire feeder may be defective.				4.	Perform the SCR Bridge Test.
					5. The control			board	may be
						faulty. See the Control Board
						LED Chart.

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con- tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-800-833-9353.

IDEALARC DC-655