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DC-400
IMA 474
TROUBLE
CAUSE
WHAT DO DO
G. Machine does not have
1. One input fuse blown.
1. Check and replace if blown after
maximum output.
checking for reason for blown fuse.
2. Open phase of main transformer
2. Check for open repair.
open.
3. Faulty Control PC Board.
3. Replace. See Procedure for
Replacing PC Boards.
4. Faulty OUTPUT control
4. Check and replace if faulty.
potentiometer.
5. Faulty OUTPUT control
5. Check and repair broken leads.
potentiometer leads 210, 211 or
75 open.
H. Machine will not shut off.
1. Input contactor contacts frozen.
1. Check and replace if necessary.
2. Defective POWER “l/0” switch,
2. Replace.
(S1).
I.
Variable or sluggish welding arc.
1. Poor work or electrode
1. Check and clean all connections.
connection.
2. Welding leads too small.
2. Check table in instruction manual.
3. Welding current or voltage too
3. Check procedures for
low.
recommended settings.
4. Defective main SCR bridge.
4. Check and replace if defective.
5. Microswitch S4C or S4D
5. Check and replace if defective.
actuator defective.
(If S4C or S4D actuator is found
defective, replace mode switch cam
also).
J. OUTPUT CONTROL not
1. OUTPUT CONTROL switch in
1. Place switch in “LOCAL”.
functioning on the machine.
wrong position.
2. Faulty OUTPUT CONTROL
2. Check and replace if found faulty.
switch.
3. Faulty OUTPUT CONTROL
3. Check and replace if found faulty.
potentiometer.
4. Leads or connections open in
4. Check lead continuity and
control circuit.
connections for an open and repair
if necessary.
5. Faulty Control PC Board.
5. Replace. See Procedure for
Replacing PC Boards.
K. OUTPUT CONTROL not
1. OUTPUT CONTROL switch in
1. Place switch in “REMOTE”.
functioning on “REMOTE”
wrong position.
2. Faulty OUTPUT CONTROL
2. Check and replace if found faulty.
switch.
3. Faulty remote control
3. Check and replace if found faulty.
potentiometer.
4. Leads or connections open in
4. Check all leads and connections,
control circuit.
internal or remote, for continuity.
Repair if necessary.
5. Faulty Control PC Board.
5. Replace. See Procedure for
Replacing PC Boards.
TROUBLESHOOTING (continued)
ARC WELDING SUPPLIES - 07 847 7870
