Lincoln Electric CLASSICII SVM125-A Service Manual page 74

F-24
ENGINE THROTTLE ADJUSTMENT TEST (continued)
6. If either of the readings is incorrect, adjust
the throttle as follows:
Adjust HIGH IDLE: Use the 10mm wrench
to loosen the locking nut. See Figure F.8 for
location of the adjusting screw and locking
nut. Turn the threaded screw counter-clock-
wise to increase the HIGH IDLE speed.
Adjust the speed until the tach reads
between 1780 and 1810 RPM. Retighten
the locking nut.
Adjust LOW IDLE: First make sure there is
no load on the machine.
switch to AUTO and wait for the engine to
change to low idle speed.
Use the 7/16" wrench to loosen the solenoid
lever arm locking nut.
Adjust the collar, to change the amount of
throw in the lever arm, until the tach reads
between 1350 and 1400 RPM. Retighten
the locking nut.
Frequency Counter Method
1. Plug the frequency counter into one of the
115 VAC auxiliary receptacles.
2. Start the engine and check the frequency
counter. At HIGH IDLE (1800 RPM), the
counter should read 60 Hz. At LOW IDLE
(1400 RPM), the counter should read 47 Hz.
Note that these are median measurements;
hertz readings may vary slightly above or
below.
3. If either of the readings is incorrect, adjust
the throttle as follows:
Adjust HIGH IDLE: Use the 10mm wrench
to loosen the locking nut. See Figure F.8
for location of the adjusting screw and lock-
ing nut. Turn the threaded screw counter-
clockwise to increase the HIGH IDLE speed.
Adjust the speed until the frequency reads
60 Hz. Retighten the locking nut.
TROUBLESHOOTING & REPAIR
Set the IDLE
See Figure F.9.
CLASSIC II
Adjust LOW IDLE: First make sure there is
no load on the machine.
switch to AUTO and wait for the engine to
change to low idle speed. Use the 7/16"
wrench to loosen the solenoid lever arm
locking nut. See Figure F.9. Adjust the col-
lar, to change the amount of throw in the
lever arm, until the frequency reads 47 Hz.
Retighten the locking nut.
Oscilloscope Method
1. Connect the oscilloscope to the 115 VAC
receptacle, 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 of these periods is incorrect, adjust
the throttle as follows:
Adjust HIGH IDLE: Use the 10mm wrench
to loosen the locking nut. See Figure F.8
for location of the adjusting screw and lock-
ing nut. Turn the threaded screw counter-
clockwise to increase the HIGH IDLE speed.
Adjust the speed until the period is 16.6 mil-
liseconds. Retighten the locking nut.
Adjust LOW IDLE: First make sure there is
no load on the machine.
switch to AUTO and wait for the engine to
change to low idle speed. Use the 7/16"
wrench to loosen the solenoid lever arm
locking nut. See Figure F.9. Adjust the col-
lar, to change the amount of throw in the
lever arm, until the period is 21.4 millisec-
onds. Retighten the locking nut.
F-24
Set the IDLE
Set the IDLE