Lincoln Electric CLASSIC III SVM 137-A Service Manual page 92

F-32
OSCILLOSCOPE METHOD
1. Connect the oscilloscope to the 115 VAC recepta-
cle, according to the manufacturer's instructions.
At HIGH IDLE (1800 RPM), the waveform should
exhibit a period of 16.6 milliseconds. At LOW IDLE
(1400 RPM), the waveform should exhibit a period
of 21.4 milliseconds. Refer to the NORMAL OPEN
CIRCUIT VOLTAGE WAVEFORM (115 VAC
SUPPLY) HIGH IDLE - NO LOAD in this section of
the manual.
2. If either if the periods is incorrect, adjust the throt-
tle as follows.
Adjust High Idle
a. Make sure there is no load on the machine.
b. Set the Idler switch to the HIGH position.
c. Locate the governor on the left side of the engine.
See Figure F.12.
d. Using the 3/8" wrench to turn the adjustment screw
and locking nut, adjust the high idle speed to
between 1780 - 1810 RPM. It may not be neces-
sary to remove the seal. See Figure F.12.
e. If further adjustments are necessary, consult the
Engine Manual.
GOVERNOR
TROUBLESHOOTING & REPAIR
FIGURE F.12 - HIGH IDLE ADJUSTMENT
Classic III and IIID
Adjust Low Idle
a. Make sure there is no load on the machine.
b. Set the Idler switch to AUTO and wait for the
engine to change to low idle speed.
c. Check the alignment of the idler rod so that the
plunger can move freely.
d. Using the 7/16" wrench, loosen the idler rod lock-
ing nut. This is located on the idler rod between
the carburetor ball joint and the idler solenoid. See
Figure F.13.
e. Rotate the carburetor shaft, and while holding it
against the idle stop screw on the carburetor,
adjust this screw to obtain low idle RPM (1325
RPM).
f. With the idler plunger fully seated, adjust idle
speed by rotating the threaded rod in the ball joint.
Lock the position by tightening the nut with the ball
joint.
g. RPM should be 1325-1475 RPM. If necessary,
adjust the idle screw to increase the idle speed by
a maximum of 50 RPM.
LOCKING
NUT
F-32
ADJUSTMENT
SCREW