Lincoln Electric RED-D-ARC DC-400 Operator's Manual page 30

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Observe all Safety Guidelines detailed throughout this manual
PROBLEMS
(SYMPTOMS)
Machine has high output or pulsing
output and no control.
Machine has low output and no
control.
Machine does not have maximum
output.
Machine will not shut off.
Variable or sluggish welding arc.
OUTPUT control not functioning on
the machine.
If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact your
Local Authorized Field Service Facility for technical troubleshooting assistance before you proceed.
TROUBLESHOOTING
POSSIBLE
CAUSE
1. Terminals 75, 76, or 77 grounded
to negative output.
1. OUTPUT CONTROL "LOCAL-
REMOTE" switch (S2) in wrong
position. Check position of
switch.
2. OUTPUT CONTROL switch
faulty. Check switch & replace if
faulty.
3. Open in feedback circuitry.
4. Faulty Control PC Board.
5. OUTPUT control potentiometer
circuit open (lead 75).
1. One input fuse blows. Check and
replace if blown after checking for
reason for blown fuse.
2. One phase of main transformer
open.
3. Faulty Control PC Board.
4. OUTPUT control potentiometer.
5. OUTPUT control potentiometer
leads 210, 211 or 75 open.
1. Input contactor contacts frozen.
2. Defective POWER "1/0" switch,
(S1).
1. Poor work or electrode connec-
tion. Place switch in "LOCAL".
2. Welding leads too small.
3. Welding current or voltage too
low.
4. Defective main SCR bridge.
5. Microswitch S4C or S4D actuator
defective.
1. OUTPUT CONTROL switch in
wrong position.
2. Faulty OUTPUT control switch.
3. Faulty OUTPUT control poten-
tiometer.
4. Leads or connections open in
control circuit.
5. Faulty Control PC Board.
CAUTION
DC-400
RECOMMENDED
COURSE OF ACTION
If all recommended possible areas of
misadjustment have been checked
and the problem persists, Contact
your local Authorized Field
Service Facility.
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