Tantalum Capacitor question.

Discussion in 'NZ Computing' started by ~misfit~, Oct 2, 2010.

  1. ~misfit~

    ~misfit~ Guest

    I've *finally* started biffing out old computer systems. 10 part-PCs went
    today (there's a place out at Paerata with a big box outside and a sign
    inviting people to drop off their old unwanted computer equipment). I've
    basically dumped everything pre-DDR RAM. They ranged from Pentium 233MMX to
    Celeron (Tualatin) 1.4GHz machines.

    I grabbed a few CPUs and RAM modules, any HDD over 40GB and some optical
    drives that worked last time they were used. I'll test the optical and hard
    drives and maybe put a 'box of bits' on Trademe. (As I drove home I thought
    about all the sub-40GB HDDs that I'd left there, some of which were actually
    from / in my 'main machine' as I upgraded over the years. I hadn't deleted /
    reformatted / wiped them and I thought briefly about turning around and
    grabbing them to wipe them. Then I realised that I really have nothing to
    hide, I didn't have a credit card in those days and it would take a long
    time to wipe all of those HDDs.)

    Sorry, I digress. My point: I'm scavenging some stuff and I noticed on a few
    older AGP cards (amongst other things) quite a few large SM tantalum
    capacitors. I wondered if it's worth unsoldering a few or do they 'drift out
    of spec' with age like electrolytics?

    (I don't have the means to test them, I really should invest in a good
    multimeter. However there are so many other things 'on the list' waiting for
    funds, like a long-overdue dentist visit that must take priority for any
    'extra' funds that come my way.)

    If anyone can answer my question please I'll know if it's worth unsoldering
    a few tants before I biff the boards into the box of stuff that I'm dropping
    off next time....


    "He who fights with monsters might take care lest he thereby become a
    monster. And if you gaze for long into an abyss, the abyss gazes also
    into you." Friedrich Wilhelm Nietzsche
    ~misfit~, Oct 2, 2010
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  2. ~misfit~

    peterwn Guest

    On Oct 2, 6:11 pm, "~misfit~"
    AFAIK they are a type of electrolytic capacitor, but without any
    'polarity'. I would there trust them no more than electrolytic
    peterwn, Oct 2, 2010
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  3. ~misfit~

    ~misfit~ Guest

    Bugger! Halfway through doing this I was in some really serious pain. Anyone
    who's not experienced chronic pain might not know this but when the pain
    gets really bad and you have to work through it, so much concentration is
    required to 'ignore' the pain that other brain functions suffer.

    So after getting back and having a cup of tea I start tidying up all the
    bits I've kept. Finally I'm going to have some room to move and work on the
    system or two that I need to get on with. First on my list is to build an
    'internet box' for the niece of a nieghbour who helps me out with any heavy
    lifting etcetera that I'd have major problems with.

    So I look around for the case that has the motherboard in it... It's an
    all-in-one MSI mATX mobo, one of the last Socket 7 mobos made that has had
    very little use. It's build quality really impressed me, especially the CPU
    VRM area that has large capacitors ali can electros that have plenty of room
    around them. All of which looked excellent. Also the four large MOSFETs that
    made up the VRM all had decent-sized heatsinks epoxied to them. It had an
    Athlon XP2400+ CPU but no RAM (I sequestered the RAM for another box that I
    was overhauling and speeding up for a friend). You might have noticed the
    use of the past tense. :-(

    It was in an anonymous, ugly-looking biege bow, with the PSU removed. I have
    a sweet little case put aside to re-build it in and an Enermax PSU.... I
    have a few trademe auctions on my watchlist for some DDR RAM....

    I was that buggered towards the end of the big sort-out that I just wanted
    to get it done, so obviously wasn't taking as much notice as I should have
    been. Yep, you guessed it, it's nowhere to be found. I'm thinking that it
    was one of the last boxes that I put in the car at a time when I was really
    struggling to keep going. It *was* in a rather nasty looking case
    considering the quality of the components.

    After wandering around the house for the third time I realised that it in
    fact isn't here anymore so, just on twilight I jumped in the car and went
    back to Paerata to see if I could grab it back. (I've driven past there
    sometimes and see that the box still has the same stuff sticking out of it
    for days at a time so I was hopeful.)

    No such luck. The box has been emptied and I didn't feel like walking up a
    long drive at twilight and trying to explain my mistake to someone I've
    never met.

    <sigh> I have another board / CPU combo here that *might* work for that
    project although I've not tested it <fingers crossed>. (I *had* fired up the
    MSI when it had RAM in it and an optical drive with a Kubuntu disc and was
    impressed with the speed with which it booted. I'd consequently spent an
    afternoon seeking out and downloading the XP drivers for it.)

    The last orthopaedic surgeon that I saw wasn't wrong when he said that my
    back has 'gone degenerative'. These last few months have been noticably
    worse than the previous few years. I've done next-to-nothing in my vegetable
    garden this year yet.

    Oh well, that's enough of a rest. I better get up and pick up all these
    computer bits that are scattered around the room and 'classify' them.....

    "He who fights with monsters might take care lest he thereby become a
    monster. And if you gaze for long into an abyss, the abyss gazes also
    into you." Friedrich Wilhelm Nietzsche
    ~misfit~, Oct 2, 2010
  4. ~misfit~

    ~misfit~ Guest

    Sorry, I was in pain and in a hurry when I wrote that. Yes, they are
    electros. However they *do* have a polarity (but unlike aluminium can
    capacitors the positive end is marked rather than the negative, a trap for
    anyone not used to them.

    The question was about how they stand up over time compared to aluminium can
    type 'wet' electros which are almost never worth scavenging.

    I've since Googled and most sources say that they're much longer-lasting
    than ali cans. Wiki says:

    "Tantalum electrolytic capacitors are less prone to "drying out" than
    aluminum capacitors, which tend to decrease in capacitance particularly when
    used in hot environments. Tantalum capacitors maintain their designed
    capacitance under such conditions over decades."


    "Tantalum capacitors can replace aluminum electrolytic capacitors in
    situations where the external environment or dense component packing results
    in a sustained hot internal environment and where high reliability is
    important. Equipment such as medical electronics and space equipment that
    require high quality and reliability make use of tantalum capacitors."

    I've used a few in the past to replace ali can electros that have failed,
    specifically in an ADSL modem / router.

    Therefore, after that research, I conclude that it's likely worth my while
    unsoldering a few of them, especially the larger ones.

    "He who fights with monsters might take care lest he thereby become a
    monster. And if you gaze for long into an abyss, the abyss gazes also
    into you." Friedrich Wilhelm Nietzsche
    ~misfit~, Oct 2, 2010
  5. ~misfit~

    PeeCee Guest

    Hi Shaun

    Being of a similar mindset to you I have for many years removed Capacitors,
    Transistors............Heatsinks, Inductors ......Screws, Brackets.........
    Hookup wire, ......... IC's, .............. from boards destined for
    Now after 40+ years of this it's becoming painfully apparent it's time to
    change this lifetime habit.

    A while ago during the exploration of long forgotten boxes in the Garage
    looking for something that was 'somewhere over there' it dawned on me I
    hadn't looked inside these boxes since I'd carefully hoarded the bits away.

    What I've come to realise is the bits are usually only useful for repairing
    'same technology' equipment, and dramatic changes in electronic hardware
    techniques means the bits are only useful for a short period after salvage.
    The price of Tant's for example drove designers to minimise their use so
    they aren't used much today, so even if you do salvage a heap of them for
    nix where do you use them?
    TTL was supplanted by CMOS then ... well you get the picture, complicated of
    course by the need for serious organisation if one is to find anything later

    I would postulate it would be better to sell any salvaged parts turning the
    resource into cash that can be used later on to buy the right bits for the
    gear in use by then.
    That way the bits get used a bit longer (by some one else) and you get less
    clutter where you can keep track of what you've got and you've got the cash
    to buy more appropriate bits.
    Think of it this way, what were those PC's you binned worth when you first
    got them? not much for sure but I'll bet you'd have got something, the PC's
    would have been used for a while longer.......................

    Of course a few bits to hand for a quick lash up......

    PeeCee, Oct 2, 2010
  6. ~misfit~

    ~misfit~ Guest

    Hey Paul.
    Yup, same here (to a certain extent), hence the clean-out, starting today.
    LOL, I seem to have this habit of hoarding for years, then throwing out just
    before the hoarded items become really rare and valuable. :-( I used to
    have about 8 shoe-boxes full of old valves / tubes, each carefully wrapped
    in tissue. About 5 years after I threw them all out they became rare as
    hen's teeth and worth quite a bit of money to folks who restore vintage
    radios etcetera.
    Well, as I mentioned, I recently replaced some bulging surface-mount ali can
    electros with tants (given to me by a regular here, along with instructions
    on use) on the PCB of an ADSL modem / router and it's been running
    flawlessly 24/7 ever since.

    This one Compaq motherboard and AGP card (from 1998) have around 20 SM tants
    on them, most quite a bit bigger than the ones I used to repair the router.
    This mobo / AGP card combo was ahead of it's time, the only caps on it (that
    I can see without putting on my $10 Warehouse reading specs) are these
    20-odd tants, six smallish SM ali cans and four honking great bit 3300uF /
    6.3V through-mount ali cans near the CPU socket.
    Yep. However more and more stuff is going SM and SM tants are superior (in
    most ways) to SM ali cans and here AM I with 20-odd SM tants, free but for
    15 minutes with the soldering iron. I know from afore-mentioned helper that
    tants certainly aren't cheap so I don't really see a down-side to this
    particular excercise.

    Believe me, I've 'been there, done that' w/r/t hoarding components.
    Especially electros after the great electro formula fiasco of the end of the
    last millenia. For a 'hobbyist' it's not only difficult but also expensive
    to buy small quantities of electronic components. Some are
    next-to-impossible to source.

    For a while there every 486 / Pentium and Pentium II board that I scrapped
    was stripped of it's capacitors which were stashed away in those little
    plastic boxes with too many compartments.

    Then, after a few failed transplants (I'd but new if I could but it wasn't
    often I could) I started to only keep Rubycon, Nichicon and Sanyo solid ali
    electros. If I got a mobo / expansion card with either brand of caps on it
    it got to be a toss-up whether to actually use it as a mobo or rather as a
    source of good Japanese electros.

    As I see it tants are a few steps up from recycled Rubycon / Nichicon ali
    electros. Especially as I've established for myself that they can be
    interchangable (and this 1998 freaky Compaq Mobo with heaps of tants tells
    me that it's likely only a current cost issue that keeps mobo manufacturers
    using ali cans over tants).
    Oh yeah, I know that song well.
    Yep, can't argue with that one. However I'm a hoarder with anxiety issues.
    Therefore I try to always keep spare hardware on-hand for my own use (in
    case of failure of whatever I'm using right now), also friends and family
    are always coming to me for repairs / upgrades / optimisation of PCs so a
    collection of spares is very handy. Alas, by the time it's not handy it's
    also not worth anything.
    Yeah, thing is, simply by dint of my lack of cash I tend to keep back-up
    systems in case my primary goes toes-up. Then, by the time the back-up is
    obsolete (by my generous terms) it's worth almost nothing.
    OMG I can't believe that you said that! Isn't there an amendment to Moore's
    Law that says that you don't ever compare the cost of a computer component
    to the relative value of it x months down the track? If there isn't there
    ..... and there's the rub. For me it's not so much what I would have got for
    them (even though that *should* be my number ONE priority) as the fact that
    they could have had a more extensive useful life. I hate the 'buy it then
    bin it' consumer society that I find myself in. :-(
    Exactly so.

    Be well,

    "He who fights with monsters might take care lest he thereby become a
    monster. And if you gaze for long into an abyss, the abyss gazes also
    into you." Friedrich Wilhelm Nietzsche
    ~misfit~, Oct 2, 2010
  7. ~misfit~

    Gib Bogle Guest

    It's so hard to throw stuff out, when it still does what it was designed and
    built to do.
    Gib Bogle, Oct 2, 2010
  8. ~misfit~

    ~misfit~ Guest

    Exactly so, that was the problem with me, getting rid of all those boxen.
    The Compaq (with the tant caps) might only have been a P 233 MMX but it
    fired straight up after being in storage for over 5 years. Same with an IBM
    Celeron 366. Both were desktop machines, built like the proverbial brick
    outhouse and weighed three times what a current mini-tower would weigh.

    I really didn't like yesterday. I'd offered some of the machines to people
    (free) but nobody wanted them. It's a shame when most of them were built so
    well (the Compaq and IBMs in particular) that they'd likely have still been
    running in a decade's time, when a new budget machines is several layers
    down in a landfill.

    Incidently, the place where I took them, there's a big sign saying drop off
    your old computer and related hardware and there's an email address and a
    cell phone number on the sign [and a name, 'Andy']. When I first
    contemplated getting rid of these machines it was the dead of winter and
    raining a lot. I emailed him asking whether he actually re-used what he
    collected of whether it was recycled for the precious metals etcetera used
    in the construction of PCs.

    In my email I said that I had a bunch of older, working machines and that I
    wanted to know because, if he re-used them I'd drop them off complete, in
    working condition at a pre-arranged time, to suit him, so that they wouldn't
    be exposed to the weather for any length of time. I didn't get a reply. I
    re-sent the email about weekly (trying from different email addresses in
    case my email had been spamtrapped) for over a month, asking for a reply,
    even one line, so I'd know whether to leave them complete or strip out the
    RAM, HDDs etc. to maybe sell on Trademe. Still no reply.

    I'd have prefered that they went on to be used frankly, even though I'd
    'lose' potential monetary gain from the sale of the RAM and CPUs etcetera on
    Trademe. However he never got back to me (and I didn't feel like phoning him
    on a cell after being ignored via email) so I stripped them. <shrug>

    "He who fights with monsters might take care lest he thereby become a
    monster. And if you gaze for long into an abyss, the abyss gazes also
    into you." Friedrich Wilhelm Nietzsche
    ~misfit~, Oct 3, 2010
  9. ~misfit~

    Gib Bogle Guest

    <snip sad story>

    I suspect that nobody in these parts is interested in a machine that can't run
    at least Windows XP. Getting rid of old stuff is a skill I'm going to have to
    learn soon, before I'm ready to be got rid of myself. I have a few old
    computers that are to be taken somewhere my wife has found where they apparently
    give them to kids to learn on, maybe taking them apart, cannibalizing etc. One
    is a Hitachi laptop. I just fired it up to see what it looked like. 133 MHz,
    Windows 95, with lots of once-useful software - MS Office, compilers and other
    tools. For sure none of this will be of the slightest interest to whoever
    receives it.

    Another category of old stuff that presents more decisions, of a different kind,
    is all that work-related material, on paper and on diskette, from years of
    self-employment. Not having looked at it for a few years, I can be pretty sure
    I'll never want to look at most of it again. But you can't be completely sure.

    Another 'old stuff' problem we have is more unusual. After living in the US for
    many years, in an old house with a fine 60s vintage gas oven, the big solid
    kind, the cooking equivalent of a V8 from the same period, we foolishly bought
    it back with us in the container, thinking we would use it. Now that we finally
    have a house with enough kitchen space to install it, we learn that being an old
    model of a brand uncommon here, it does not have certification. No gas fitter
    will install it, without it first going through the certification process,
    which, we're told, would cost much more than it's worth. This is almost a
    collectable piece - in fact we've collected it and are storing it in the garage,
    where it quietly rusts. I haven't yet adjusted to the idea of dumping it, but
    I'd be happy to give it away to anyone who wants it, maybe someone who's happy
    to break the law and fit it himself. A friend in the US would like it, but
    packing and freighting it would cost too much. It's not just garage space that
    this stuff takes up, it's also brain space.
    Gib Bogle, Oct 3, 2010
  10. ~misfit~

    ~misfit~ Guest

    LOL, yeah, it can get complicated. Good luck with the oven.

    "He who fights with monsters might take care lest he thereby become a
    monster. And if you gaze for long into an abyss, the abyss gazes also
    into you." Friedrich Wilhelm Nietzsche
    ~misfit~, Oct 3, 2010
  11. ~misfit~

    Squiggle Guest

    Not according to the manufacturers.. in fact an old tantalum is a
    good tantalum according to the information I have read.
    They apparently do not suffer from the normal bathtub failure curve
    that most things do, if they survive past the infant mortality stage
    the failure rate declines to almost nothing.. and never increases. (I
    figure it must increase eventually, even if it is just from external
    corrosion of the leads).

    So if you can get them off, and into the new circuit without stressing
    them thermally they should be fine to use again. One of the biggest
    problems with tants is the fact they tend to fail short-circuit, not
    open circuit, which means if they fail they often take the components
    around them out as well.

    They are low ESR capacitors (way better than ali electrolytics at high
    frequency), and you can often get away with a smaller value tant than
    you could with an ali electrolytic for ripple removal.


    Squiggle, Oct 3, 2010
  12. ~misfit~

    ~misfit~ Guest

    Thanks Squigs, that does indeed help. I shall unsolder them before the
    boards go off for recycling, taking care not to overheat them. Good to know
    that last bit too. :)

    "He who fights with monsters might take care lest he thereby become a
    monster. And if you gaze for long into an abyss, the abyss gazes also
    into you." Friedrich Wilhelm Nietzsche
    ~misfit~, Oct 4, 2010
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