1978 Johnson 4HP outboards Service Manual, Page 33Get this manual
DESCRIPTION The magneto Capacitor Discharge (C .D Ignition System consists of five major componentsThey are: 1Flywheel AssemblyContains two magnets, cast into the flywheel 180 degrees apartThese magnets are magnetically charged of opposite polaritySee Figure 4-1 2Charge Coil Assemblylarge coil of wire which generates Alternating Current (A.C that is sent into the Power PackSee Figure 4-13Sensor Assemblysmall coil of wire which generates the triggering voltage for the Power Pack See Figure 4-1 4Power Pack Assembly (C .D.2)Contains the electronic circuits necessary to produce ignition at the proper time:
aCapacitor Charge Circuit bTriggering Circuit cCapacitor Discharge (C .D Circuit 5Ignition CoilsGenerate the very high voltage required to ignite the fuel in each cylinder
THEORY OF OPERATION