Lincoln LT-7 Troubleshooting Manual page 21

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Troubleshooting Guide –
components. See Wiring Diagrams for troubleshooting of specific circuits.
PROBLEMS
(SYMPTOMS)
The wire feeds at full speed during
the inch mode (only).
The wire feeds at full speed during
the weld mode (only).
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. The logic board may be faulty.
1. Remove electrode from drive
rolls and place a jumper wire
from lead #528 to lead #539 on
the reed switch(CR3) in the
shunt box. Press the start
switch and observe lights 2L
and 2D on the logic board.
Both lights should be on. If light
2D is lit and light 2L is NOT lit
the logic board may be faulty.
2. If light 2D does not light check
continuity (zero ohms) of leads
#528 and #539 from the reed
switch (CR3) to the logic board.
See wiring diagram.
LT-7 TRACTOR
RECOMMENDED SHOP
COURSE OF ACTION
1. Check the wiring between the
logic board and the control board.
See wiring diagram.
2. Perform the Wire Drive Motor
Test.
1. Check leads #634, #641 and
2. Check R3 rheostat for correct
CAUTION
Observe Safety Guidelines
detailed in the beginning of this manual.
#642 between wire feed speed
control (R3) and logic board.
resistance (5000 ohms) and
proper function.
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