The problem as seen in post #561 by Nyemi's scope trace clearly shows that the signal is not being turned off, causing the high current drain on the HV board, heating the transistor like a dead short. The low speed pulse signal, below 200 rpms is the trouble spot in the sensor input routine. There are about 10 lines or so, according to my neighbor that are suspect to cause the condition. The signal must be turned off after every trigger in low rpm mode or this problem, although a random occurance, is holding the SCR gate connection and draining the charge on the capacitor a cross the coil leads. There is a positive way to correct this and a solution to the latch up. Could be fixed by the weekend, as soon as he gets time for his scope hookup to test it.

John