Kohler Courage SV710-740 Service Manual page 65

4. Turn the key switch to the ON position and
check for 12 volts at the center/power (red) lead
terminal of the DSAI module. Use the same
ground location for the multi-meter as in Step 3.
a. If all tests are OK and module has no spark or
fails to advance, replace the affected module.
b. If any of the tests are bad; determine cause
and fix as required, then retest.
DSAM, previously known as Smart-Spark
equipped engines utilize an electronic capacitive
discharge ignition system with electronic spark
advance. A typical application (Figure 7-9) consists of
the following components:
• A magnet assembly which is permanently affixed
to the flywheel.
• Two electronic capacitive discharge ignition
modules which mount on the engine crankcase
(Figure 7-9).
• A spark advance module which mounts to the
engine shrouding (Figure 7-9).
• A 12 volt battery which supplies current to the
spark advance module.
• A kill switch (or key switch) which grounds the
spark advance module to stop the engine.
• Two spark plugs.
Operation: The ignition module for this system
operates in the same fashion as the fixed timing
module, except the trigger circuit for the
semi-conductor (L2, Figure 7-5) is replaced by the
spark advance module (Figure 7-9).
The pulse generated by the input coil of the ignition
module (L1, Figure 7-5) is fed to the input of the
conditioning circuit. The conditioning circuit shapes
this pulse, putting it in a useable form for the
additional circuits. This pulse starts the charge pump,
which charges a capacitor in a linear fashion that is
directly related to the engine speed. At the same time
the pulse resets the delay circuit for the length of the
pulse width. The capacitor is off during this period
and no output is generated. As soon as the original
pulse drops back to zero, the capacitor in the delay
circuit begins to charge.
When the charge on the delay capacitor exceeds the
charge on the charge pump capacitor, the capacitor
changes state, activating the pulse generator.
This pulse turns "ON" the CD ignition module
semi-conductor. Energy is then transferred to the
secondary output transformer (T1, Figure 7-5). The
high voltage pulse generated here is delivered to
the spark plug, causing arcing of the spark gap
and igniting the fuel-air mixture in the combustion
chamber. As the trigger pulse is generated, all
associated circuits are reset, their capacitors
discharged. The longer it takes the delay circuit to
surpass the charge pump capacitor voltage, the later
the trigger pulse will occur, retarding the timing
accordingly.