Chainsaw Repair

Jeff, the blue coil I have here is marked SEM Amal Sweden 10110500 L02

The box next to the flywheel referred to by HVA as 'electronics box', it has NO spark plug wire, usually only a wire to the actual coil (mounted remotely) and a wire to the on/off switch. Its function is to generate a current pulse. As the flywheel magnets start past it, it begins to generate current and sends it to the coil, after the magnets pass the electronics box it abruptly stops generating current which 'triggers' the HT pulse from the coil which results in the spark at the plug? When the on/off switch is in the 'off' position the current pulse generated by the flywheel passage is shunted directly to ground, no spark occurs and the engine stops.

Two part ignition systems are most probably a result of what was possible with the electronics technology available at the time and restrictions on available space on the saw. Today, technology, miniaturization and packaging have advanced to the point that one piece ignitions are the norm.

Gotcha, never heard of the primary coil being called the "trigger"    it's just a common primary/secondary coil that is triggered by the collapse of the magnetic field! You guys had me thinking this was some sort of advanced way before its time coil that had some sort of super trick triggering device or something!!!!  Lol 

I think it is just the terminology that Dolmar happens to use for that particular part.

Makes sense now! Appreciate the clarification.  Adam

Remember to look at the coil to see what the SEM part # is.