Lincoln LT-7 Troubleshooting Manual page 28

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Troubleshooting Guide –
components. See Wiring Diagrams for troubleshooting of specific circuits.
PROBLEMS
(SYMPTOMS)
The travel circuit breaker repeated-
ly trips.
The travel motor runs at full speed
with 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 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
TRAVEL PROBLEMS
1. While unit is traveling check the
the travel motor armature cur-
rent. Normal current is 0.5
amps DC.
(Note: In older units also
check for field voltage of 90 to
110VDC at leads #656 to
#657. If field voltage is missing
check field fuse F401 on travel
board).
2. If the current is too high check
for possible excessive external
loading of the travel motor such
as gummed up gears, excessive
cable drag or other obstacles.
3. The travel board may be faulty.
1. Remove power to unit and
check the resistance of travel
speed control rheostat (R6).
Normal resistance is 5000
ohms. Also check R6 for
smooth operation.
2. Check associated leads
between R6 and the travel
board.
3. The travel board may be faulty.
LT-7 TRACTOR
RECOMMENDED SHOP
COURSE OF ACTION
1. If all tests are good the circuit
1. Perform the Travel Motor Test .
CAUTION
Observe Safety Guidelines
detailed in the beginning of this manual.
breaker may be faulty. Test or
replace.
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