Lincoln Electric IM420-D manual Board Troubleshooting Guide, Electric Shock can kill

E-5	TROUBLESHOOTING	E-5
	Observe all Safety Guidelines detailed throughout this manual

P.C. BOARD TROUBLESHOOTING GUIDE

WARNING

ELECTRIC SHOCK can kill.

•Have an electrician install and service this equipment.

•Turn the input power off at the fuse box before working on equipment.

•Do not touch electrically hot parts.

---------------------------------------------------------------------

Machine settings for P.C. board troubleshooting. Disconnect all leads to the wire feeder and jumper ter- minals #2 and #4 on DC-1000. Output Control at DC- 1000. Mode switch in the CV(I) position.

CONTROL/FAULT PROTECTION P.C. BOARD

1.LED1 indicates AC input voltage is present at pins 255-256. If not lit, check the voltage across the secondary winding of the control transformer, T2. The voltage should be approximately 115 volts. If not, the problem is in the power supply and not the P.C. board.

2.LED2 indicates welder output voltage is being sup- plied to the control circuit. If not lit, check to make certain lead 222 from pin 2 of the 15-pin control circuit P.C. board connector is connected to the power source negative output lead and is not bro- ken.

3.LED3 indicates power is being applied to fault pro- tection pilot relay 2CR to turn on the input contac- tor.

4.LED4 indicates when overcurrent protection circuit is being activated.

5.LED5 indicates a control signal is being supplied to the firing circuit. As the output control is varied, LED5 should change brilliancy from bright at low output to dim at high output.

1.Lights 7, 8, and 9 indicate AC power being sup- plied to the P.C. boards from T1 auxiliary winding. If a light is not lit, turn the machine off and unplug P5 from J5 on the firing P.C. board. Turn the machine on and check the following voltages:

Light That	Check AC Voltage	Voltage Should
Was Off	Between Pins of	Be Approx.
	Plug P5
7	P5 Pins 2 & 4	75 VAC
	(Wires 203, 204)
8	P5 Pins 7 & 3	75 VAC
	(Wires 205, 206)
9	P5 Pins 9 & 8	75 VAC
	(Wires 207, 208)

•If approximately 75 VAC is present, turn the machine off, plug P5 back into firing board. Turn the machine back on and check to see if the light or lights are on. If the light or lights are not on replace the firing P.C. board.

•If the 75 VAC was not present, then check the wiring.

2.Lights 1 through 6 indicate gate signals are being supplied to the main power SCR’s 1 through 6 respectively. If light 5 on the control circuit and lights 7 through 9 on the firing circuit are lit and lights 1 through 6 are not lit, check lead 231 between the firing circuit and the control circuit that it is not broken and is connected to each Molex connector. If the lead shows continuity and lights 1 through 6 are not lit, replace the firing cir- cuit P.C. board. If any one of the lights 1 through 6 is not lit and lights 7 through 9 are lit, replace the firing circuit P.C. board.

FIRING CIRCUIT P.C. BOARD

All nine light emitting diodes must be lit when the power source is turned on and the wire feed arc start button is pressed or a jumper is connected between 2 and 4.

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact your Local Lincoln Authorized Field Service Facility for technical troubleshooting assistance before you proceed.

IDEALARC® DC-1000