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Do exist tantal caps, that are "bad caps"?

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    #1

    Do exist tantal caps, that are "bad caps"?

    Guys, I wonder, if there are tantalum caps, that are known to be bad caps. The case in point is Sony Vaio PCG-7144M notebook, that show clear sign of bad caps.

    Upon start, the Vista progressbad freezes repeatedly and continue booting upon keypress...

    Once Vista booted, I fire up Prime95 and both mem and CPU tests fail in just a seconds. Plus the NTB is acting weird.

    All that I would immediatelly contribute to the "bad caps" plague and I would claim that upon cap replacement, the NTB should work as desired.

    However upon opening the NTB it seems that on the PCB are (with one 100uF SMD cap) only tantalum caps. And I cannot recall that these tantalum caps could be are dying or being bad at all and I have hard time to believe that all these problems are because of ONE SMD cap that did not even looks bad in the first place...

    Suggestions?
    "It is dangerous to be right in matters on which the established authorities are wrong." - Voltaire
    "I believe that all the people who stand to profit by a war and who help provoke it should be shot on the first day it starts..." - Hemingway my config - my caps
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    #2
    Re: Do exist tantal caps, that are "bad caps"?

    I've not heard of a particular brand or series of tantalum caps being notoriously bad. Tantalum itself is an expensive commodity of poor availability, so I don't think it really encourages the making of crappy knock-offs. Back in the late 90s Sun Micro realized that tantalum caps had a poorly understood (and incendiary) failure mechanism, and they banned the use of tantalum caps from their products. But tantalum caps seem not to be subtle in failure. So if you aren't looking at ashes where the cap in question is/was I'd be inclined to think the problem you're trying to fix is something else. Might the power input connector be getting flaky?
    PeteS in CA

    Power Supplies should be boring: No loud noises, no bright flashes, and no bad smells.
    ****************************
    To kill personal responsibility, initiative or success, punish it by taxing it. To encourage irresponsibility, improvidence, dependence and failure, reward it by subsidizing it.
    ****************************

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      #3
      Re: Do exist tantal caps, that are "bad caps"?

      I don't know of any particular make of bad tantalum caps. They fail short circuit and burn up, so it's easy to see bad ones- unless they got banged up and cracked in two, especially in notebooks/laptops that have been dropped.

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        #4
        Re: Do exist tantal caps, that are "bad caps"?

        Can wet tantalum capacitors go bad?
        My first choice in quality Japanese electrolytics is Nippon Chemi-Con, which has been in business since 1931... the quality of electronics is dependent on the quality of the electrolytics.

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          #5
          Re: Do exist tantal caps, that are "bad caps"?

          There are even something like wet tantalum caps?
          "It is dangerous to be right in matters on which the established authorities are wrong." - Voltaire
          "I believe that all the people who stand to profit by a war and who help provoke it should be shot on the first day it starts..." - Hemingway my config - my caps

          Comment

            #6
            Re: Do exist tantal caps, that are "bad caps"?

            Yes, there are.. but they're quite expensive...
            for example:

            http://www.digikey.com/product-detai...967-ND/1879540
            http://www.digikey.com/product-detai...696-ND/2092184
            http://www.digikey.com/product-detai...794-ND/1587094

            They're quite different compared to regular tantalum capacitors. If you're curious, you can read about them here:

            Intro to wet tantalums :

            And they do have failures, just like regular tantalums, see attached pdf (in the zip file) ... or go to https://cdn.badcaps-static.com/pdfs/...6bbd542eb7.pdf (invalid certificate)
            Attached Files
            Last edited by mariushm; 09-16-2013, 03:27 PM.

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              #7
              Re: Do exist tantal caps, that are "bad caps"?

              And those $60-$130 ea. wet tantalums are commercial parts. That ability to operate down to -55C makes them popular in military electronics ... imagine how pricey mil-spec wet tantalums are.

              Like aluminum electrolytics, wet tantalums don't like reverse voltages or above-rating voltages. Many years ago I had some blow up - misinstalled - in front of me. My ears were ringing for an hour, and even though I washed the board very quickly, the electrolyte pitted the voltage planes of the top layer of the board. VERY! NASTY! THINGS!
              PeteS in CA

              Power Supplies should be boring: No loud noises, no bright flashes, and no bad smells.
              ****************************
              To kill personal responsibility, initiative or success, punish it by taxing it. To encourage irresponsibility, improvidence, dependence and failure, reward it by subsidizing it.
              ****************************

              Comment

                #8
                Re: Do exist tantal caps, that are "bad caps"?

                Well, there ARE fake tantalum capacitors out there.
                Muh-soggy-knee

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