Re: Explain the 'CD' ignition system, what is 'CD'?
Good information from hightrim. The question asked in addition to that, "what is CD"
On a conventional old battery/coil ignition system the coil operated on 12 volts from the battery. Breaker points interrupted the 12 volts and each time that happened a high voltage was created in a second winding in the coil, which provided the spark across the spark plug gap.
Enter CD: As you found out there are several ways to accomplish this, but the basic deal is that instead of the coil operating on 12 volts a high voltage is supplied to it--usually around 300 volts. The 300 volts pulse creates a high voltage in the second winding as above. Without getting into electronic theory, lets just say that's better.
So, how do we find a 300 volt supply in a boat with a 12 volt battery? Early systems took the 12 volts and amplified it to 300 volts. That 300 volts was stored in a capacitor until time to fire the plug. Then by some sort of triggering device, the 300 volts was discharged through the coil. Hence "capacitor discharge".
The triggering device changed often but it is either a set of breaker points or some sort of magnetic sensor or light interrupter. Again, lets not get too deep here.
Enter Mag CD: This is what you have. Instead of amplifying 12 volts to 300, these motors generate the 300 volts by using special coils under the flywheel, called "charge coils". From there on, the scheme is the same, store it in a capacitor and discharge it upon a trigger signal from sensor coils also under the flywheel. The big advantage is reduced electronics and the motor runs independently of the battery. You can even rope start it with a completely dead battery.
The CD systems have come a long way from the beginning and the electronics have changed a whole big bunch. They have been pretty much established with the Mag CD similar to yours.
Hope this gives you some basic information without making it complicated.
Cheap and easy to fix! Who needs 300 volts!
