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OUTPUT PROBLEMS
Observe Safety Guidelines detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS)
POSSIBLE AREAS OF
MISADJUSTMENT(S)
RECOMMENDED
COURSE OF ACTION
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.
CAUTION
TROUBLESHOOTING AND REPAIR
F-7 F-7
CLASSIC® 300D & 300G
The weld output is considerably
less than indicated on the dials
or varies abnormally. Auxiliary
output appears normal.
Check welding cables for
damaged or poor connections.
Welding cable may be
excessively long, too small, or
coiled. Try using a set of
short test cables of adequate
size.
If a remote current control is
being used, try switching to
local control. The remote
current control may be faulty.
The engine may not be
maintaining steady RPM.
Make sure there is an
adequate supply of clean,
fresh fuel. Replace fuel filters
if necessary. Have engine
serviced by a qualified engine
technician.
Perform the Engine RPM
Adjustment Test.
Check the exciter brushes
and, if necessary, perform the
Exciter Brush and Slip Ring
Service Procedure.
Check the welding generator
brushes and, if necessary,
perform the Welding
Generator Brush and
Commutator Inspection and
Service procedure.
Check all the large weld
current carrying leads inside
the machine for damaged
conductors, insulation, and
poor connections.
Check the wiring that
connects the exciter, field
bridge rectifier, rheostat,
remote/local switch, and the
shunt coils. Check for
damaged conductors,
insulation, and poor
connections.
Replace the Exciter Diode
Bridge with a new or known
good bridge.
(Diode bridges will sometimes
appear good under test, but
fail while under a normal
operating load.)
Check the 64 Ohm fine
current control rheostat,
replace if necessary.
Check remote/local switch.
Replace if necessary.
Perform the Exciter Rotor
Resistance and Ground
Test.
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