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FIGURE F.9 - 115VAC SUPPLY WAVEFORM (HIGH IDLE- NO LOAD)
ENGINE THROTTLE ADJUSTMENT TEST (continued)
Oscilloscope Method:
1. Connect the oscilloscope to the 115 VAC recepta-
cle, according to the manufacturer’s instructions.
At 3700 RPM, the waveform should exhibit a peri-
od of 16.2 milliseconds. At 2400 RPM, the wave-
form should exhibit a period of 25.0 milliseconds.
Refer to NORMAL OPEN CIRCUIT VOLTAGE
WAVEFORM (115 VAC SUPPLY) HIGH IDLE – NO
LOAD in this section of the manual.
2. If either waveform periods is incorrect, adjust the
throttle as follows:
Adjust HIGH IDLE: Use the 3/8” wrench to turn the
spring-loaded adjustment nut. See Figure F.8 for
location of the adjustment nut. Adjust the speed
until the period is 16.2 milliseconds.
Adjust LOW IDLE: First make sure there is no load
on the machine. Set the IDLER switch to AUTO
and wait for the engine to change to low idle speed.
Use the 3/8” wrench to adjust the solenoid nut,
which changes the amount of throw in the throttle
lever arm. See Figure F.8 for location of the
adjustment nut. Adjust the speed until the period is
27.3 milliseconds.
Vibratach Method:
1. Place the vibratach as close to the engine as pos-
sible. With the machine case top removed, the top
of the air cleaner is the best location.
2. Start the engine and observe the whip handle of
the vibratach. At HIGH IDLE (3700 RPM), the whip
handle should exhibit maximum oscillation. At
LOW IDLE (2400 RPM), the whip handle should
exhibit minimum oscillation.
Note that these are median measurements; vibrat-
ach readings may vary slightly above or below:
3. If either of the vibratach indications is incorrect,
adjust the throttle as follows:
Adjust HIGH IDLE: Use the 3/8” wrench to turn the
spring-loaded adjustment nut. See Figure F.8 for
location of the adjustment nut. Turn the nut clock-
wise to increase HIGH IDLE speed. Adjust the
speed until the vibratach whip handle exhibits max-
imum oscillation at 3700 to 3750 RPM.
Adjust LOW IDLE: First make sure that there is no
load on the machine. Set the IDLER switch to
AUTO and wait for the engine to change to low idle
speed. Use the 3/8” wrench to adjust the solenoid
nut, which changes the amount of throw in the
throttle lever arm. See Figure F.8 for location of
the adjustment nut. Adjust the speed until the
vibratach whip handle exhibits minimum oscillation
at 2150 to 2400 RPM.
TROUBLESHOOTING AND REPAIR
F-28 F-28
RANGER® 3 PHASE
CH1
0 volts
5 ms
50 volts
16.2 ms
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