WELDING MACHINE LINCOLN DC-600 TROUBLE SHOOTING GUIDE

Trouble	Cause	What to Do
Input contactor (1CR) chatter	1. Faulty input contactor (1CR) 2. Low line voltage 3. Faulty relay (2CR)	1. Repair or replace 2. Check input power 3. Replace relay
Machine input contactor does not operate.	1. Supply line fuse blown 2. Contactor power circuit dead 3. Broken power lead 4. Wrong input voltage 5. Primary or secondary thermostats open 6. Open input contactor coil. 7. Faulty start/stop pushbutton switch 8. Faulty 2CR relay 9. Defective control board	1. Replace if blown – look for reason first 2. Check pilot transformer T2 and associated leads. 3. Check input voltage at contactor. 4. Check input voltage against nameplate and input connection 5. Check for overheating; make sure fan is operating and there is no obstruction to free air flow. Replace faulty thermostats. 6. Replace coil 7. Replace switch 8. Replace relay 9. Replace control board
Input contactor pulls in when start button is pressed, but immediately drops out.	1. Defective start/stop pushbutton 2. Defective 1CR interlock 3. with 2-4 jumpered, terminal 75, 76, or 77 grouded to negative output 4. Short on output terminal with 2-4 jumpered. 5. Defective control board.	1. Check and replace if necessary. 2. Repair or replace. 3. Check 75,76,or 77 for ground to negative output circuit 4. Remove short. 5. Replace
Machine input contactor operates but no output when trying to weld	1. Electrode or work lead loose or broken. 2. Open main transformer T1 primary or secondary circuit. 3. Output pilot relay (4CR) not operating or faulty. 4. Firing circuit PC board not connected or is faulty.	1. Repair connection. 2. Repair. 3. Check relay by connecting a jumper across terminals 2 and 4 on DC-600 terminal strip. Replace if faulty. 4. All nine light emitting diodes (LED1 thru LED9) must be lit. See PC board Trouble Shooting Guide.
Machine has maximum output but no control.	1. Output control switch (SW4) is wrong position 2. Output control switch faulty. 3. Open in feedback circuitry 4. Faulty control or firing circuit PC boards. 5. Output control potentiometer circuit open (Lead 75)	1. Check position of switch 2. Check switch and replace if faulty 3. Check wiring and control and firing circuit PC 4. All light emitting diodes must lit, except LED4 on the control/fault board See PC board Trouble Shooting Guide. 5. Check and replace potentiometer if faulty. Check wiring of Lead#75