Generac 86640 - Manual (Page 93)

Enqine Control Circuit Board (Continued)
See Figure 11 on previous page. The service technician
hould be aware of the following features on the engine
ontrol circuit board:
1. An adjustment potentiometer (R19) is provided to permit
adjustment of the rpm at which an overspeed shut down will
occur.
a. Automatic shutdown should occur when AC frequency
(engine speed) exceeds approximately 69-71 Hertz (2070-
2130 rpm).
b. Adjustment is required whenever the engine control
circuit board is replaced.
2. The circuit board mounts a red crank lamp (LED) which
should turn on when the engine is cranking.
a. A “Lamp On" condition indicates that (a) the Wire 17
circuit has been grounded by start-stop switch action, and
(b) circuit board action has delivered battery voltage to the
Wire No. 56 circuit to initiate cranking.
b. The lamp should go out when the start-stop switch is
released and cranking has terminated.
3. The circuit board mounts a green run iamp (LED).
a. The run lamp should illuminate when circuit board action
has delivered 12 volts DC to the Wire No. 14 circuit (to open
the carburetor fuel valve, and turn on the fuel pump).
b. If the run lamp does NOT turn on during cranking, engine
will not start.
Overspeed Shutdown Adjustment
To adjust the overspeed shutdown setting, proceed as
follows:
1. On the engine control circuit board, turn the OVERSPEED
SHUTDOWN POT counterclockwise until it just contacts its
stop. DO NOT FORCE.
2. Connect an accurate AC frequency meter across the
generator’s AC output leads.
3. Start the engine, let it stabilize and warm up at no-load.
4. SLOWLY increase engine speed until the frequency meter
reads 69-71 Hertz.
5. Hold the throttle at 69-71 Hertz, then SLOWLY turn the
OVERSPEED SHUTDOWN POT clockwise. When the en­
gine shuts down, overspeed setting is correct.
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