Test 16 - Check Stepper Motor Control; (V-Twin Engine Units) - Generac Power Systems 10 kW LP Repair Manual

sEctioN 2.4
DiaGNostic tEsts
GOVERNOR
SHAFT
GOVERNOR
CLAMP
BOLT
Figure 10. Engine Governor Adjustment Single
Cylinder Engines
PROCEDURE
(8 kW UNITS WITH DUAL GOVERNOR SPRINGS):
1. Loosen the governor clamp bolt (Figure 10).
2. Hold the governor lever at its wide open throttle position,
and rotate the governor shaft clockwise as far as it will
go. Then, tighten the governor lever clamp bolt to 70
inch-pounds (8 N-m).
3. Start the generator; let it stabilize and warm up at
no-load.
4. Connect a frequency meter across the generators AC
output leads.
5. Turn the primary adjust screw to obtain a frequency
reading of 61.5 Hz. Turn the secondary adjust screw to
obtain a frequency reading of 62.5 Hz.
6. When frequency is correct at no load, check the AC
voltage reading. If voltage is incorrect, the voltage
regulator may require adjustment.
RESULTS:
1. If, after adjusting the engine governor, frequency and
voltage are good, tests may be discontinued.
2. If frequency is now good, but voltage is high or low, refer
back to flow chart.
3. If engine was overspeeding, check linkage and throttle
for binding. If no governor response is indicated refer to
engine service manual.
4. If engine appears to run rough and results in low fre-
quency, proceed to Problem 18, Section 4.3.
Page 50
SECONDARY
ADJUST SCREW
PRIMARY
ADJUST
SCREW
Part 2
teSt 16 – check Stepper motor
control (V-tWin enGine unitS)
PROCEDURE:
1. Remove air cleaner cover to access stepper motor.
2. Physically grab the throttle and verify the stepper motor,
linkage and throttle do not bind in any way, if any binding
is felt repair or replace components as needed. Some
resistance should be felt as the stepper motor moves
through it's travel.
3. Physically move the throttle to the closed position by
pulling the stepper motor arm towards the idle stop. See
Figures 11 and 12 (for 9/10 kW units) or Figure 13 (for
12-20 kW Units).
4. Place the AUTO-OFF-MANUAL switch to MANUAL and
watch for stepper motor movement. It should move to
the wide open position during cranking. Once the unit
starts the stepper motor should move the throttle to a
position to maintain 60 Hertz.
5. If no movement is seen in Step 4 remove the control
panel cover. Verify the six pin connector on the printed
circuit board is seated properly, remove the connector
and then replace it and test again. Verify the switches
are correctly set.
6. If problem continues the remove six pin connector from
the printed circuit board. Set Volt meter to measure
ohms. Carefully measure from the end of the six pin
harness as follows:
note: press down with the meter leads on the
connectors exposed terminals, do not probe into
the connector.
a. Connect one meter lead to Red, connect the
remaining test lead to Orange, approximately
10 ohms should be measured.
b. Connect one meter lead to Red, connect the
remaining test lead to Yellow, approximately 10
ohms should be measured.
c. Connect one meter lead to Red, connect the
remaining test lead to Brown, approximately 10
ohms should be measured.
d. Connect one meter lead to Red, connect the
remaining test lead to Black, approximately 10
ohms should be measured.
e. Connect one meter lead to Red, connect the
remaining test to the stepper motor case. No resis-
tance should be measured INFINITY or Open.
RESULTS:
1. If the stepper motor fails any part of Step 6 replace the
stepper motor.
2. If the stepper motor passes all steps replace the Printed
Circuit Board.
AC GENERATORS