Re: 1977 9.9 Johnson ignition troubleshooting procedure

[David Stanton]

quote outbdnut2:

quote outbdnut2:

quote fleetwin:

Be careful with the terms/names here…When you say “driver coil”, I think of the low tension ignition used on earlier models. The part you are referring to is called the “sensor coil”. I’m not trying to be a grammar geek, just want to avoid confusion. Did you do the resistance tests on the sensor and charge coils? If so, I am assuming they checked out OK, these parts are simple and don’t fail very often.

Thanks for the insight. By Driver coil, I meant the coil that generates the voltage that gets stored in the capacitor that the SCR discharges to the ignition coils when the sensor coil tells it to. I have not started troubleshooting at all yet, and just assumed this coil would be accessible. Does the sensor coil do double-duty and also generate this voltage?
My experience with CD ignitions goes back to the Delta Mark 10 aftermarket automotive units of the 1970s where I could access all the discrete parts to troubleshoot. Back then, myself and about 20 other electrical engineers like myself at Honeywell got a price break ordering over 30 of these units and put them on our cars. Since I coordinated the order, when a few of them broke down over the next couple of years, I was the one that got to troubleshoot and repair them. The main difference is these old automotive units had 12 volts available and used a power inverter circuit to convert to AC and feed a step-up transformer to get 400 volts for the discharge capacitor – these units also used the existing car’s breaker points to trigger, so no sense coil. I’d like to see the complete electronic circuit that is potted up in the Johnson armature plate and/or power pack just for my own curiousity.
Dave