[jmchrist]

Originally Posted by ischmitz

jmchrist, I don't see how anything connected to pin 7 under static conditions (coil, resistor) could produce negative bias of 100mV. The circuit does not provide any negative voltage relative to ground.

Of course. My apologies for asking this stupid question.

What I am saying is that the trigger happens at a negative voltage. See the SPICE output examples:

http://forums.pelicanparts.com/uploads12/schem1196897821.jpg

http://forums.pelicanparts.com/uploads12/scope1196897832.jpg

The value of R6 is between 10k (brown) and 51k (yellow) with 22k (green) as standard value. You can see how the trigger pulse gets delayed as R6 gets smaller.

Ingo

Very interesting simulation indeed, with a very good agreement with the scope observation, as you said before.
The picture I provided in a post above is apparently also in agreement when having a closer look to it. However the picture is not precise enough. Next time I have a 6-pin CDI to repair I'll make a closer area picture.

Now your simulation incite me to ask a new question (hopefully less stupid as my previous one) :
What could have been the motivation of the designers of this CDI for providing for a fine tuning of R5/R6 (at final stage of manufacturing ?) since the influence on the triggering input voltage level is so weak ?