Lincoln LT-7, Troubleshooting Manual

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TROUBLESHOOTING AND REPAIR
Observe Safety Guidelines
detailed in the beginning of this manual.
Troubleshooting Guide –
See Wiring Diagrams for location of specified
components. See Wiring Diagrams for troubleshooting of specific circuits.
B-9 B-9
LT-7 TRACTOR
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
CAUTION
FUNCTIONAL PROBLEMS
PROBLEMS
(SYMPTOMS) FIELD
COURSE OF ACTION RECOMMENDED SHOP
COURSE OF ACTION
The wire will not inch down. The
wire inches up properly. When the
start switch is pressed the wire
feeds up instead of down. 1. Check the connections between
the power source and LT7 for
loose or incorrect connections.
2. Check the leads connected to
the variable voltage board for
loose or faulty connections.
3. While pressing the inch down
switch observe light 3A on the
variable voltage board.
• If light 3A is NOT lit check
leads #21 and #67 for conti-
nuity to the voltage board.
4. If while pressing the inch down
switch light 3A does light also
check light 2E on the logic
board.
• If light 3A and 2E are both lit
the control board may be
faulty.
• If light 3A is lit but light 2E is
NOT lit the logic board may
be faulty.
1. Check lead #21 for continuity
(zero ohms) to “work”.
2. Check lead #67 for continuity
(zero ohms) to electrode.