Johnson J2R4SUC 2007, Руководство по обслуживанию

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56
IGNITION AND ELECTRICAL
OPERATION
When the recoil starter is pulled, the flywheel is turned. An electromotive force generated in the primary
winding (n
1
) of the ignition coil makes the transistor (TR
1
) conduct through the resistor (R
1
) and forms the
primary circuit (indicated by dashed lines).
As the flywheel turns further, the primary current increases, and the terminal voltage of the circuit con-
sisting of the resistor (R
1
) and transistor (TR
1
) increases. This increases the working voltage at the con-
nection of the series circuit (R
2
and R
3
) connected in parallel to the primary circuit. As the flywheel turns
further, the terminal voltage of the resistor (R
3
) in the resistor circuit (R
2
and R
3
) rises to the level of work-
ing voltage of the transistor (TR
2
) when the ignition timing approaches, and thus the transistor (TR
2
) is
turned on. As a result, the base current of (TR
1
) flowing through the resistor (R
1
) is bypassed, and the
transistor (TR
1
) is turned off from the conductive state.
The current flowing through the primary winding (n
1
) is thus interrupted, and a rapid change occurs in the
magnetic flux across the ignition coil. The result is a high surge voltage in the secondary winding (n
2
).
Transistor
Flywheel
magneto
Ignition
coil
Spark
plug Emergency
stop switch