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ignition amp 700

posted by  Alfixit on  Sun Mar 23 16:28 CST 2003
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last visit: Mon Feb 4 13:00 CST 2008
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Hi BB,
I read a post in the 700faqs that mentioned heat sink compound behind the ignition amplifier next to the aircleaner. Is this necessary, or just a good idea?
Today I cleaned the front of the engine compartment in my 7. Cleaned all grounds, cleaned all connections. Wife went to store, car has SERIOUS problem accelerating. Researched 700faqs, thought about it, check ignition amplifier beside airbox. I was able to move it, I must have cleaned out the dirt that was securing it. Removed it, cleaned the area, replaced it. Car is now a like a 6 cylinder wannabe.
It doesn't look like there was a heat transfer compound on it originally, it is just the original painted surface.
--
Al Hagenberger '84 245 309K, '87 744 171K








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    ignition amp 700

    posted by  chris herbst on  Tue Mar 25 17:25 CST 2003
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    last visit: Mon Oct 20 20:32 CST 2014
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    Whatever. Don't listen to me anymore. See JohnB's post.

    --
    chris herbst, near chicago








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      ignition amp 700

      posted by  Alfixit on  Fri Mar 28 18:31 CST 2003
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      last visit: Mon Feb 4 13:00 CST 2008
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      The module/heat sink connection was solid. It was loose at the body connection. I guess it just needs a good ground at that point, 'cause it sure made "my" (it's my wife's ride)car run like the timing was off.
      I sure as hell wouldn't pressure wash my engine compartment, indiscriminately or otherwise. By "clean the engine compartment" what I meant was remove almost everything except the engine, tubing, and wiring. Then I clean and wipe down all of the nice painted parts of the frame and body. Clean everything I took out and reassemble it. 171K still looks good(300K wagon still looks good, but only in the engine compartment).
      --
      Al Hagenberger '84 245 309K, '87 744 171K








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    ignition amp 700

    posted by  chris herbst on  Sun Mar 23 17:21 CST 2003
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    last visit: Mon Oct 20 20:32 CST 2014
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    To answer your question, it isn't necessary to have heatsink compound behind the power stage. You're right about there not being any in the first place; there never was. But I suppose it can't hurt to do so, since that is their job. Plus it would increase heat transfer capability quite a bit since it doesn't exactly sit against a finely machined surface or anything.

    --
    chris herbst, near chicago








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      wrong about ignition module heat sink compound...it was there when it was new! 700

      posted by  someone claiming to be JohnB on  Mon Mar 24 05:42 CST 2003 [RELATED]

      I've replaced at least two of them, one an 87 760T, another 90 740T. Both replacements had some type of dielectric/conductive paste between the IC and the heat sink. One of the reasons the new IC's come with a new heat sink, apparently.

      Pressure washing the engine indiscriminately will apparently clear the compound from the IC/heat sink. The IC can then overheat/thermal runaway, leading to intermittent engine cutout. Shut the engine off, let it cool or freeze-spray the ignition module and it may work again, or may be fried.








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        Oh wow, you got me good there! 700

        posted by  chris herbst on  Tue Mar 25 17:24 CST 2003
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        last visit: Mon Oct 20 20:32 CST 2014
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        Why not post it proudly in the main thread instead?

        One thing I try to avoid is embarassing people unless they say something that is way out of line, personal, or just plain preposterous (sales pitches about alternative refrigerants, stupid product plugs, etc.) This comes from working in a professional shop where people's whole LIVES are dictated by how many people they can make fools of in the course of an average day, and having to work with them.

        The condescending, Fisher-Price "Explanation" of how a heatsink works (for us ignorant folks) was a nice touch back to pre-college electronics.

        And the best part--I was speaking of where the unit mounts to the body of the car.

        --
        chris herbst, near chicago








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          Oh wow, you got me good there! 700

          posted by  john sargent on  Tue Mar 25 17:36 CST 2003
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          last visit: Wed Oct 22 09:07 CST 2014
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          I thought your post refered to the heat sink against the chassis, where no heat transfer compound is found. Yes, there is compound between the ignition amp and the heat sink.

          From time to time a newbie will respond to one of my posts, and talk to me like I have never worked on one of these cars. Sometimes I can't restrain myself and drop kick them. Just like this post by swede4.






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