Newbie - Ignition Control Unit ? - Mercedes-Benz Forum

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post #1 of 4 (permalink) Old 10-25-2006, 10:45 PM Thread Starter
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Newbie - Ignition Control Unit ?

Hello everyone. Allow me to introduce myself. My name is Raffi, and Im trying to help my friend figure out a problem with his car. It is a 1971 Mercedes 250. Immaculate car. He is in the process of completing a restoration, but has ran into a problem. We tracked it down to the Ignition Control Unit. I did some research first on this website for this issue, and someone had said to check all the soldering connections on the board, as that is usually the main cause of the problem.

Upon opening the casing of the unit we noticed had the transistor that is under the dust cover is defective. We wouldnt mind soldering on a new transistor, but we are unable to locate one. We checked all the electronic stores near our town, and checked online also. The only ones we can find were 2 prong transistors. The Mercedes requires a 3-prong.
The ID numbers on the transistor are as follows.
An exact replacement or a subsitute would be great.
We would appreciate all the help. I can post a picture of the exact part if needed. I will also post some pics of the car if anyone desires.
Thank you much.
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post #2 of 4 (permalink) Old 10-27-2006, 01:36 PM
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I would reccomend replacing the entire system with a Pertronix Ignitor system. You will eliminate the points and ignition amplifier and have a much more reliable ignition system. Not sure if one is available for your car-I'm sure someone here knows.
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post #3 of 4 (permalink) Old 12-29-2006, 04:24 PM
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Transistors only come with three leads. I would recommend doing a general search on the internet for appropriate transistor replacements. You could also try Radio Shack, or a TV repair shop - both should have huge books for direct replacements.

As for Pertronix units, I would swear by them. I replaced my points, condensor and such, with a Pertronix unit. FANTASTIC stuff.
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post #4 of 4 (permalink) Old 12-29-2006, 05:53 PM
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You're probably looking at a large darlington transistor. The transistor's case is the third lead (the collector). The old www. mbz. org site had a description of how to do what you're doing. Buying a used unit from ebay for 30$ is probably simpler though. -CTH

PS. There are three versions of the box available for older cars. They are interchangable with some wiring adjustments. However, it's simpler to keep the same box. Watch the last three digits on the part number (014, 015 or 016).

Last edited by cth; 12-29-2006 at 05:55 PM.
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