Jawa Thyristor

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So your 20 year old Soviet Block electronics have failed...the end right? Not so comrades! The CDI ignition on Jawa is an elegantly simple system, and may I add robust too! It has lasted 20+ years after all hasn't it? Being simple puts building a suitable replacement well within the grasp of pretty much anyone. It's cheap as well! Here is how its done:

Parts needed

Capacitor $3.98

Diode $0.22

Thyristor! $0.36

You will need one each of the above, the prices are of course subject change without notice and do not include shipping, you get the picture though.

You will need to know how to solder if you want the unit to be reliable, If you don't know how to solder and don't want to learn, you can use crimp connectors. (Seriously, a soldering kit costs about $15 and it will take you about 20 minutes to develop the skill necessary for this)

Thymaster.jpg Here we have a drawing (albeit a poor one) of the new thyristor. The one critical is the connection between the Diode, Thyristor and capacitor. The center lead of the Thyristor is soldered to the banded end of the Diode as well as one end of the Capacitor. The illustration is drawn with the metal side of the Thyristor up, you can package or arrange it anyway you want, so long as the connections are made in this way. You may choose to use a heat sink on the thyristor, however, bear in mind that the the metal plate on the back of the thyristor is connected internally to the center lead so that if it touches ground in any way the unit will not function. Leaving the unit in in open air is already better cooling than being encased in epoxy, and even with that design weakness it still lasted 20 years. I would suggest soldering the unit directly but other types of connectors may be used, I would also suggest ordering multiple thyristors and set up the unit in such a manner as to make the thyristor replaceable.

Categories: Jawa