Lincoln Electric IDEALARC R3R 500-I Operating Manual page 14

PROBLEMS
(SYMPTOMS)
C. Machine input contactor closes but has
no or low output. Open circuit voltage
should be 67 to 71 volts.
D. Machine has maximum output
but no control.
Page 14
TROUBLESHOOTING
POSSIBLE
CAUSE
FUNCTION PROBLEMS
1. Electrode or work lead loose or broken.
2. Open transformer primary or secondary
circuit.
3. Supply line fuse blown.
4. Input line grounded causing single
phase input.
5. Input leads not connected to contactor.
6. Latching resistor, R3, open.
7. Control circuit problems.
1. Possible defective power SCR.
2. Possible defective control board.
Idealarc R3R 500-I & 600-I
RECOMMENDED
COURSE OF ACTION
1. Repair connections.
2. Repair.
3. Replace blown fuse – check fuse size.
4. Repair input to machine.
5. Connect input lead.
6. a. Replace.
b. Check leads to the resistor and repair
if defective.
7. See Troubleshooting Procedures –
Power Silicon Controlled Rectifier (Page
?).
1. Remove all gate leads G1, G2 and G3
at PC board connector. If welder has
any open circuit voltage, power SCR is
defective. See Troubleshooting
Procedures Page ?.
2. See PC board Troubleshooting
Procedures Page ?.
IM 6000