ignition module

Good old flyback system. Look up transistorized ignition or something along those lines...

There are a few possible options. My guess is that it is a CDI (Capacitive Discharge Ignition) unit. It uses a high-current capacitor and a thyristor. If you google it, you'll find more info.

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RoRo

Can you link to some of the testing how-to articles? Can you find out what kind of sensor triggers your module: magnetic, hall effect, optical? For what it's worth, the module itself surely has a high-voltage semiconductor (perhaps an IGBT or an SCR) and ancillary circuitry. I'm guessing the ignition coil itself is a separate part and not contained in the potted module. The aforementioned sensor detects the moment when the piston is positioned for firing and sends a signal to the module. The module fires the ignition coil in one of two ways, either the dwell method, or by dumping the charge from a high voltage capacitor into it. Sorry I couldn't be more specific, but I don't know much about chainsaws.

d

The ignition module has a high voltage lead to the spark plug. A terminal that the kill switch connects to, and a ground terminal. It is situated about .030 inch away from the flywheel, which has embeded magnets. There are no points or separate sensor for flywheel position. It may or may not have a capactor or some sort of semiconductor in the module. There is no separate ignition coil.

The testing links just say disconnect the kill terminal , pull the spark plug, and pull the starting rope while observing the spark plug. If there is no spark , the module is bad. Replace module. If there is a good spark, then hook up the kill terminal and see if there is still a spark. No spark , then the problem is in the kill switch.

I suspect there could be a 4 layer diode in the module. But that is why I am asking if anyone knows.

Dan

The ignition module has a high voltage lead to the spark plug. A terminal that the kill switch connects to, and a ground terminal. It is situated about .030 inch away from the flywheel, which has embeded magnets. There are no points or separate sensor for flywheel position. It may or may not have a capactor or some sort of semiconductor in the module. There is no separate ignition coil.

The testing links just say disconnect the kill terminal , pull the spark plug, and pull the starting rope while observing the spark plug. If there is no spark , the module is bad. Replace module. If there is a good spark, then hook up the kill terminal and see if there is still a spark. No spark , then the problem is in the kill switch.

I suspect there could be a 4 layer diode in the module. But that is why I am asking if anyone knows.

Dan

It could have a diode or diodes, but they would be a small part of what's in the module. The magnets on the flywheel serve one of two purposes: they are either a reluctor that sets the timing, or else, they are a magneto. Since I don't have experience with magnetos, I'll describe a little bit about ignition that uses a reluctor. First, you can go to this link

about two thirds of the way down there's a section on magnetic pickups. If the module has a magnetic pickup, it's a small coil. As the flywheel magnets whip past the pickup in the module, the moving magnetic field causes a surge of voltage in the pickup coil. Those pulses don't produce the spark, they merely set the timing for your spark. The spark comes from an ignition coil. This is true of any ignition, whether dwell, CDI or magneto. They all use ignition coils. You said there's a wire from the module direct to the sparkplug, so the ignition coil may be contained in the module. There is a circuit in there as well, that detects the timing pulse from the pickup coil and fires the ignition coil at the appropriate times. As I said, I'm not a magneto expert. If it's a magneto, maybe there's no pickup, just an ignition coil driven directly by the flywheel magnets. I kind of doubt it though.