Pc Board Troubleshooting Guide - Lincoln Electric SVM188-A Service Manual

F-6
Observe Safety Guidelines detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS)
Machine input contactor operates
but machine has no weld output with
the Output terminal Switch ON. Fan
runs and pilot light glows.
NOTE: Alternate Trigger methods.
• Operate Wire Feeder trigger.
• Place a jumper across 2 & 4 on
the terminal strip T.S.2. or
across pins C & D in 14 pin con-
nector.
The machine does not have maxi-
mum weld output.
The weld output terminals are
always electrically "hot".
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. Check LED 10 on the Firing
Board and LED 6 on the Control
Board. Both Should be ON.
2. Check all of the LEDs on both
PC Boards for proper operation.
1. Check all three phase input
lines at the DC600.
sure input voltages match
machine rating and recon-
nect panel.
2. Put LOCAL/REMOTE Switch
(SW3) in "LOCAL" position.
If problem is solved then
check remote control unit or
wire feeder.
1. Remove any external leads
hooked to #2 and #4 on the ter-
minal strip. If the problem dis-
appears the fault is in the control
cable or wire feeder.
2. If some open circuit voltage is
present (over 3VDC.) after per-
forming Step #1. then the prob-
lem is within the DC600.
CAUTION
DC-600
RECOMMENDED
COURSE OF ACTION
1. If both LEDs are OFF,tr y an
alternate method of triggering.
If LEDs come ON and machine
weld output is restored check
the Weld Terminal Switch (S2)
and the associated wiring. If not,
see the Internal Trigger Circuit
Test.If both LEDs are ON and
there is still no output go to Step
2.
2. The Firing Board or Control
Board may be defective. See the
PC Board Troubleshooting
Guide.
1. Check the Output Control
Make Potentiometer
associated wiring for loose or
faulty connections.
wiring diagram.
3. Perform the Control Board
Test.
4. Perform the Firing Board Test.
5. Perform the
Bridge Test.
6. Perform the Main Transformer
Test.
1. Check for an internal short
between leads #2 and #4. See
wiring diagram.
3. Perform Firing Board Test.
4. Perform Control Board Test.
5. Perform the
Bridge Test.
6. The SCR Snubber(s) may be
"leaky". Check or replace.
F-6
(R1) and
See
SCR Output
SCR Output