Current Range Selector; Fine Current Adjustment; Engine Idler Circuit - Lincoln Electric CLASSIC I SVM134-A Service Manual

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ENGINE, MAIN GENERATOR
ARMATURE AND FRAME AND DC
EXCITER (CONTINUED)

CURRENT RANGE SELECTOR

The selector switch acts as a course current adjust-
ment by allowing varying amounts of series windings to
be included in the welding current path. The series
coils and selector switch are connected in series with
the negative output terminal.

FINE CURRENT ADJUSTMENT

The field rheostat control functions as a fine output cur-
rent adjustment by controlling the current through the
shunt windings, thus controlling the amount of magnet-
ism created in the shunt field windings. Open circuit
weld voltage can also be controlled by the field rheo-
stat control.
THEORY OF OPERATION

ENGINE IDLER CIRCUIT

The idler solenoid is mechanically connected to the
engine governor linkage.
being drawn, the reed switch CR2 is closed. This
signals the idler PC board to release (deactivate) the
idler solenoid, which then lets the machine go to a high
speed condition. Also, when auxiliary power (115VDC)
is being used, the current is passed through a reed
switch coil located on the idler PC board, which signals
the PC board to release the idler solenoid.
When welding ceases or the auxiliary load is removed,
a preset time delay of about 15 seconds starts. After
approximately 15 seconds, the idler PC board acti-
vates the idler solenoid, and the machine will return to
a low idle speed condition.
CLASSIC I
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When welding current is