Kohler CV11-16, Service Manual

Page: 66 / 150

8.6
Section 8
Electrical System and Components
Operation
As the fl ywheel rotates, the magnet grouping passes
the input coil (L1) of the ignition module, inducing
energy in the coil. The resultant pulse is rectifi ed by
diode (D1) and charges capacitor (C1). Current from
the same pulse also travels through the brown lead
to the spark advance module (SAM), and enters the
input of the conditioning circuit. The conditioning
circuit shapes this pulse, putting it in a useable form
for the other circuits. The ‘‘conditioned’’ pulse starts
the charge pump, which charges a capacitor in linear
fashion, directly related to engine speed. The pulse
also resets the delay circuit. The comparator is off
during this period.
When the fl ywheel magnet group has passed the
input coil, and the original pulse drops back to zero,
the capacitor in the delay circuit begins to charge off
of the power source. When the charge on the delay
capacitor exceeds the charge pump capacitor, the
comparator changes state and activates the pulse
generator, The ‘‘generated’’ pulse returns to the
ignition module through the yellow lead and turns
‘‘on’’ the semiconductor switch (SCS), completing
the circuits between the charging capacitor (C1)
and the transformer (T1). The charging capacitor
discharges into the transformer primary (P), inducing
a high-voltage pulse in the transformer secondary (S).
The high-voltage pulse arcs across the spark plug
gap, igniting the fuel-air mixture in the combustion
chamber. The longer it takes the delay circuit to
surpass the reference voltage in the charge pump
capacitor, the later the trigger pulse will occur,
retarding the timing accordingly.
The trigger pulse exiting the SAM activates the reset
circuit, discharging the capacitor and resetting the
circuits for the next cycle.
Figure 8-7.
Spark
Advance
Module
(SAM)
L
1
R1
SCS
D1
Yellow Brown
C1
T1
P S
S
park
Plug
Charge
Pump
Reset
Circuit
Comparator
Delay
Circuit Conditioning
Circuit
B
rown
From
Input
Coil
Power
Source
P
ulse
Generator
V+ (7.2 V)
Green or
Black
B+ (12 VDC)
Red
Yellow To Semi-
Conductor
Switch