1997 Johnson Evinrude "EU" 90 thru 115 90 CV Service Manual, P/N 507267, Page 101Get this manual
Sensor Coil
The sensor coil is located on the timer base assemblyIt consists of many windings of wire wrapped around metal laminationOnce the flywheel exceeds minimum cranking RPM, the flywheel's magnetic lines of force cut through the sensor coil windings to produce voltageThis voltage is supplied to the power pack to control small electronic switches (SCR's) which, in turn, direct power pack output to the correct ignition coil primary The timer base has four sensor coils; one per cylinderPower Pack The power pack
has three major functions:
The power pack receives its operating voltage from the charge coil and converts it into direct current for storage The power pack stores this direct current in capacitor The power pack uses series of electronic switches (SCR's), activated by sensor coil output, to select the correct ignition coil primary winding for firing The power pack has one SCR for each ignition coil it controlsKey Switch