Here some info regarding the measurements, measured on the following point's.
With use of the original pickup signal (from testing machine)
-Channel 4 is incoming signal pickup on the IC (Pin19)
-Channel 2 is Pickup signal it self (whit/red wire pickup)
-Channel 1 is Thyristor Gate (switch for discharging the capacitor)
-Channel 3 is outgoing signal ignition on the IC (Pin29)
Describing a typical behavior On the Yamaha CDI's, specially on the low RPM's
Need to investigate this better, as its a interesting point.
All signals are there, only the IC is not generating a Outgoing ignition signal. (Ch3)
So the tyristor gate is trickered at the back off the lobe. (lower part signal)
Still the ignition is working on the back off the lobe.
The IC is not giving a signal.
Her the IC starts making a ignition signal (starting at 33,33Hz) but still the tyristor is firing at the back off the lobe.
You can see the signal on the tyristor gate from the IC but it has no effect. (as it is later)
Still the thyristor is firing at the back off the lobe, IC outgoing signal has no effect.
At 59,2Hz the back off the lobe signal has stopped. (at 58,50Hz it is gone)
Now the IC outgoing signal is controlling the ignition.
IC is still controlling the Ignition.
IC still controlling.
The back off the lobe is firing the ignition till 58,5Hz (that is a 3500rpm) after a 58,5Hz it jumps to the outgoing IC signal.
That jump you see on the scope is a relative big one, will need to investigate this further