Lincoln Electric VANTAGE SVM178-B Service Manual page 216

F-28
ENGINE THROTTLE ADJUSTMENT TEST PROCEDURE (CONTINUED)
PROCEDURE
Oscilloscope Method
1. Connect the oscilloscope to the 115 VAC recepta-
cle, according to the manufacturer's instructions.
At HIGH IDLE (1900 RPM), the waveform should
exhibit a period of 15.8 milliseconds. At LOW IDLE
(1475 RPM), the waveform should exhibit a period
of 20.3 milliseconds. Refer to the NORMAL OPEN
CIRCUIT VOLTAGE WAVEFORM (115 VAC SUP-
PLY) HIGH IDLE - NO LOAD below.
2. If either of these waveform periods is incorrect,
adjust the throttle as follows:
NORMAL OPEN CIRCUIT VOLTAGE WAVEFORM (115VAC SUPPLY)
This is the typical auxiliary output voltage generated from a properly operating
machine.
Note that each vertical division represents 50 volts and that each horizontal divi-
sion represents 5 milliseconds in time.
Note: Scope probes are connected at machine 115VAC receptacle.
TROUBLESHOOTING AND REPAIR
HIGH IDLE – NO LOAD
15.8 ms
50V
VANTAGE® 500
Adjust HIGH IDLE: Use the 10mm wrench to
loosen the locking nut. See Figure F.7 for location
of the adjusting screw and locking nut. Turn the
threaded screw counter-clockwise to increase the
HIGH IDLE speed. Adjust the speed until the peri-
od is 15.8 milliseconds. Retighten the locking nut.
Adjust LOW IDLE: First make sure there is no load
on the machine. Set the IDLE switch to AUTO and
wait for the engine to change to low idle speed.
Use the 10mm wrench to loosen the solenoid lever
arm locking nut. See Figure F.7 Adjust the collar,
to change the amount of throw in the lever arm,
until the period is 20.3 milliseconds. Retighten the
locking nut.
5ms
F-28
0 volts