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Crown CE2000 PA Amp Question - thermal glue?

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  • Crown CE2000 PA Amp Question - thermal glue?

    I am repairing a crown CE2000 amplifier. There are four transistors encased in what looks like silicone glue; attaching them to the power transistor heat sink. I'm assuming this is to draw away heat. However, I don't know what was used to 'glue' them in place. This is not thermal grease/compound because it is hard/rubbery. These are bias transistors 2N3904 (Q104,Q204). What is this glue and where do I get it?

    Thanks
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    VOLUME 4 U

  • #2
    RTV.
    It's not a silicone glue,
    it's silicone. Like silicone caulking.
    That's how it gets when it cures.
    Rubbery.

    Here is the assembly note: CE2000 RTV.pdf
    Last edited by Jazz P Bass; 09-03-2016, 01:56 AM.

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    • #3
      ok, thanks. Replacing that transistor didn't solve my problem of -35 VDC on channel two.

      Here's the story:
      On initial testing, Found -99 VDC seen on channel two speaker output. After removing circuit board discovered Q232 transistor was burnt/broken and C223 cap bulging.

      I've rebuilt negative side of channel two replacing Q223-28, R267-R272, R407-R412, D215, Q232, Q231, C223, R259, R400, R265, Q220, Q221, R261, R262 : Now getting -33.8 VDC (dropping slowly) on channel two output. Replaced D214, D215, Q204, R284, Q212. Still getting - 35VDC. Thinking I need to rebuild the positive side of channel two but resistance readings seem to match negative side. (base to emitter & case to emitter on MJ21194). What am I missing?

      Search for Crown CE2000 on google for service manual. Don't know how to post a .pdf here.

      Thanks
      Last edited by PfeifferElectronics; 09-13-2016, 01:20 AM.
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      VOLUME 4 U

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      • #4
        How about a few voltage measurements?

        Start with Q104 & Q107.
        EBC.
        Q108 & Q109/
        EBC of both.
        Then complete the picture with the driver transistors.
        Q110 & Q112.
        Q120 & Q121.
        Lastly, Q111.

        After all that, study what you observed. Something will leap out at you.

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        • #5
          CE 2000_B_sch.zip

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          • #6
            setting up test environment tonight.... have to extend conductors so I can take readings when board is out of chassis. thanks so much for your help. I do this part-time for local musicians.. always learning.
            ---------------------------
            VOLUME 4 U

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