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Thread: Selecting replacement electrolytic caps for IBM 9585-K planar

  1. #1

    Exclamation Selecting replacement electrolytic caps for IBM 9585-K planar

    http://ps-2.kev009.com/ohlandl/9585/...con_Capacitors

    My replacement 85-K planar just got here today, and I was looking it over. Fairly nice shape, BUT three 7mm long electrolytic caps seem to have vented a little on the leads. This was not wonderfull, but the link above is to capacitors of the same make, ratings, and locations leaking...In the earlier instance, one cap voided itself, with the spooge running under the Surface Mount F/W SCSI controller chip...


    Nichicon 10uF, 25v, 105C electrolytic capacitors, N245, 7mm long

    C293 under U84
    C503 by upper right corner of internal F/W connector.
    C504 by U131

    I have seen scattered comments about Nichicon 7mm caps leaking in '91 era automotive applications. All the other electrolytic caps on the board are longer (12-15mm or so), and none of the other caps vented.

    So. Since all the IBM designers are retired, or dead, or retired -AND- dead, we can't ask them.

    One could chalk this up to designing on the edge, and the edge is pretty steep.

    Can I replace this with a 10uF, 30 plus volt cap? The temp rating of 105 C was plenty good. Plenty of clearance, the closest surface is about 2" away (or even more!).

    It may be this run of capacitors was mis-marked, but the original planar was mid '93, this one mid '94. Or it might be that there was a bit more ripple than expected, and that heated the cap up...

  2. #2
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    There was also a spate of Chinese counterfeit Nichicons as well.
    As long as the working voltage is higher (within limits), there's no problem.

  3. #3

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    Quote Originally Posted by Chuck(G) View Post
    There was also a spate of Chinese counterfeit Nichicons as well.
    That issue was around 2000-2001, I believe.

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