Lincoln LT-7 Troubleshooting Manual page 23

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Troubleshooting Guide –
components. See Wiring Diagrams for troubleshooting of specific circuits.
PROBLEMS
(SYMPTOMS)
The wire feeds up instead of down
when the start switch is pressed.
There is no voltage reading on LT7
voltmeter. The wire inches up and
down properly.
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 electrical technical troubleshooting assistance before you proceed.Call 216-383-2531 or 1-800-
833-9353
TROUBLESHOOTING AND REPAIR
See Wiring Diagrams for location of specified
FIELD
COURSE OF ACTION
FUNCTIONAL PROBLEMS
1. Check for proper connection of
electrode leads and control
cable leads from power source
to LT7.
2. On Lincoln power sources put a
jumper from #2 to #4 on the ter-
minal strip. This activates the
output from the power source.
Test for voltage at the output
terminals of the power source.
If no voltage is indicated then
the power source is faulty.
3. If voltage is present at the
power source output terminals it
should also be present at the
LT7 voltmeter. If not, check
leads #21 and #67 for breaks or
faulty connections.
4. Remove electrode from drive
rolls and press the start switch.
Observe light 2K on the logic
board. It should be lit. If light
2K does NOT light when the
start switch is pressed remove
power to unit. Remove lead
#682 from CR1. Check the
resistance of the coil from the
terminal to lead #510. Normal
resistance is 10,000 ohms. See
wiring diagram.
5. If the relay coil resistance is cor-
rect the logic board may be
faulty.
6. If light 2K does light make sure
the relay (CR1) contacts are
making contact.
LT-7 TRACTOR
RECOMMENDED SHOP
COURSE OF ACTION
1. Check lead #21 for continuity
2. Check lead #67 for continuity
3. Check leads #2 and #4 for
CAUTION
Observe Safety Guidelines
detailed in the beginning of this manual.
(zero ohms) to "work".
(zero ohms) to electrode.
loose or faulty connections
between relay CR1 and the
control cable receptacle.
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