TM 5-3431-207-15
Section IV. TROUBLESHOOTING
trouble symptom stated is followed by a list of probable
60. General
causes of trouble shown in the left-hand column. The
Paragraphs 61 through 66 provides information
possible remedy recommended is given opposite the
useful in diagnosing and correcting unsatisfactory
cause in the right-hand column.
operations or failure of equipment or any of its
components.
Each
61. Motor Fails to Hold the "Heat" Constantly
Probable cause
Possible remedy
Rough or dirty commutator.
Commutator should be trued or cleaned
Field circuit may have variable resistance
Check field current with ammeter to
connection, or intermittent open-circuit,
discover varying current. This applies to
due to loose connections or broken wire.
Brush-shifting or other mechanical current-
used.
adjusting mechanism may have loose or
Check current adjusting mechanism for
worn links.
backlash and play.
Current control brush holder contact springs
may be worn out or bent. Contact surface
Inspect, replace needed parts, clean internal
may be dirty, rough or pitted.
contact surface of control device. 'Do not
Motor regulator rheostat shorting switch out
lubricate. Smooth up roughened surface.
of adjustment.
Adjust switch contacts or mercury
switch tilt angle so circuit is open
when motor is at full speed and when
welding.
62. Welder Starts But Fails to Generate Current
Probable cause
Possible remedy
May be running the wrong way.
Check direction of rotation with manu-
facturer's instructions or direction arrow.
On three-phase motors, directions may be
changed by interchanging any two input
leads.
Polarity reversing switch may be in the
Place handle in up or down position.
neutral position.
Exciter may have lost excitation.
Flash the field with a storage battery or
another generator, first with one polarity
and then with another to see if it "builds
up" (flash exciter field, if
set
has
separate exciter).
Reversing switch wiper contact bent and not
This shorts the exciter series and causes
clearing the blade of switch when switch
failure to generate-bend or replace to
is closed.
secure correct operation.
63. Welding Arc is Loud and Splatters Excessively
Probable cause
Possible remedy
Current setting may be too high.
Check setting and current output with
Polarity may be wrong.
Check polarity, Try reversing polarity or try
an electrode of the opposite polarity.
Motor regulator shorting switch contacts
Adjust so contacts are well open or mercury
close intermittently when running at full
level below contact on mercury tilt switch
speed, causes increasing surge of current
when motor is at full speed position of
and splatter.
motor regulator (bellows fully (extended).
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