Seems like that could be remedied with a more robust SCR that can take the surge current. Curious if the Bosch power supply limits its output if heavily loaded? I assume it would. That's another protective feature. Fred
Quote:
Originally Posted by Bob Ashlock
This is a 6-pin Bosch CDI, correct? (Not an 8-pin? ...the 8-pin does not 'squeal' with power applied unless you have distributor rotor rotation.)
My thoughts:
The box only requires ground at terminal 31/1 and +12V on terminal 15 to operate the converter, but it is not always easy to hear them squeal... they operate around 3.5 - 4 Khz and sometimes the transformer just doesn't make a lot of noise.
A shorted coil will definitely 'take out' the CDI unit. It will cause the thyristor to fail (shorted) and then the converter will try to push power into the short and it won't 'squeal' like normal.
The silver coils are notorious for shorting and (more often) arcing internally, resulting in no spark out of the high-tension terminal.
Remove the 'A' lead to the coil. Connect an Ohmmeter from ground to the CDI "A" lead and see if you have a short or very low Ohms. If you do, the SCR/thrysitor has gone bye-bye.
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