Lincoln Electric SVM188-A Service Manual page 47

F-7
Observe Safety Guidelines detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS)
Machine has maximum weld output
and no control.
Machine has minimum output and
no control.
If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely,
contact the Lincoln Electric Service Department for technical troubleshooting assistance before you proceed.
Call 1-888-935-3877.
TROUBLESHOOTING AND REPAIR
POSSIBLE AREAS OF
MISADJUSTMENT(S)
OUTPUT PROBLEMS
1. If remote control is being used
set LOCALl/REMOTE SWITCH
(SW3) to 'LOCAL' position and
try to control weld output using
the Output Control
Potentiometer (R1) at the
DC600. If the problem is solved
check the remote control unit
(or wire feeder) and associated
control cable.
1. If a remote control unit is NOT
connected to the DC-600, the
LOCAL/REMOTE Switch must
be in the "LOCAL" position.
2. If a remote control cable is con-
nected, the control leads may
be "shorted" to the positive weld
output.
3. Make certain the three phase
input voltage is correct and
matches the machine rating and
the reconnect panel.
CAUTION
DC-600
RECOMMENDED
COURSE OF ACTION
1. Check the LOCAL/REMOTE
Switch (SW3) and associated
wiring.
2. Check feedback leads #222
(negative output
#215, and #210 (output shunt)
for loose or faulty connections.
See Wiring Diagram.
3. Check the #75 lead for continu-
ity (zero ohms) from the Output
Control Potentiometer (R1) to
the control board connector
J1,Pin2. See Wiring Diagram.
4. Possible defective
Board or Firing Board. See the
PC Board Troubleshooting
Guide.
5. Perform the SCR
Bridge Test.
1. Check the Output
Potentiometer (R1) and associ-
ated wiring.
2. Check the LOCAL/REMOTE
Switch (SW3), the Weld Mode
Switch (SW4) and associated
wiring.
3. Perform the Control Board
Test.
4. Perform the Firing Board Test.
5. Perform the SCR
Bridge Test.
6. Perform the Main Transformer
Test.
F-7
terminal),
Control
Output
Control
Output