Capacitor question

Discussion in 'General Electronics Chat' started by riplin, Jul 5, 2010.

  1. riplin

    Thread Starter New Member

    Jul 5, 2010
    2
    0
    Hello community, I'm a total electronics newb and have a quick question. I have a leaking capacitor on one of my computer mobo's and its causing strange lockup issues I believe with the machine. The cap has markings on it that say 6.3v 1800uf. I have some old mobo's lying around and I found one with 6.3v 1500uf. Would it work if i swapped out the 1800 for the 1500 good one?


    Thanks

    Riplin
     
  2. Jaguarjoe

    Active Member

    Apr 7, 2010
    770
    90
    A 1500 uF good capacitor is better than a dead 1800uF unit. Try it and see. If it doesn't work your not out anything and more than likely with the value of these so close to each other, it will work.
     
  3. Potato Pudding

    Well-Known Member

    Jun 11, 2010
    684
    92
    It is a part that you could buy new for only a few dollars if you wanted to be more certain it would work.

    Keep in mind that you could find cascade failures.

    One part that dies tends to stress other parts.

    And if you have one bad capacitor you might see more. Look for bulging on any Electro caps.
     
  4. riplin

    Thread Starter New Member

    Jul 5, 2010
    2
    0
    k thanks.

    Yes I'm going to get the proper one at a local electronics store tomorrow. Other caps look ok its just one particular one

    Thanks gain for your replies

    Riplin
     
  5. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    You're really best off to order electrolytic capacitors from large, high-volume authorized distributors. You want fresh capacitors. If you buy a cap that's been sitting on a shelf for awhile, it may just blow up the first time you apply power.

    A 1500uF cap is not a suitable replacement for an 1800uF cap for a computer mobo. The ripple would be increased by 17%, and the temp of the capacitor increased due to the increased ripple current. It might work, but I'll suggest that it will not be as stable or reliable as replacing it with a part that was specified in the original design.
     
  6. studiot

    AAC Fanatic!

    Nov 9, 2007
    5,005
    513
    Computer capacitors have a higher temperature spec than normal components so a corner store replacement will fail early.

    http://www.badcaps.net/
     
    Potato Pudding likes this.
  7. Potato Pudding

    Well-Known Member

    Jun 11, 2010
    684
    92

    I did not know that. COOL! Learning stuff makes me feel smarter.

    Thanks because planning to replace some motherboard caps is one of the things that has gotten me interested in Electronics again after years away, and you have increased my chances of a successful repair.
     
  8. Norfindel

    Active Member

    Mar 6, 2008
    235
    9
    Take the capacitor with you, and buy one with the same parameters. It's common to find low-esr, high-temperature capacitors inside computers. Double-check that you're connecting them with the right polarity. Some manufacturers mark the positive pin, some the negative. The positive is generally longer.
     
  9. Dx3

    Member

    Jun 19, 2010
    87
    7
    I have saved more than one computer by replacing a row of capacitors. Good luck!
     
  10. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    It's the type of cap which determines which terminal gets the stripe.
    Aluminum electrolytic capacitors generally have a stripe on the negative terminal.
    Tantalum caps have the positive terminal striped.

    Both will explode with a bang and a flash if connected backwards.
     
  11. Norfindel

    Active Member

    Mar 6, 2008
    235
    9
    That's interesting, i had always assumed that the manufacturers did as they seem fit. I always check for a + or - sign, and the lenght of the leg, just to be sure.

    Yeah, i had my days of checking what was the most awesome-exploding capacitor when i was in secondary education :D
     
  12. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
    312
    Aww. jeez.. I hope you wore eye protection.

    Nothing like sitting in the emergency room getting pieces of aluminum or tantalum out of your eye.

    Well hey, you've got one more. ;)

    Stereoscopic vision is SO over-rated!
     
  13. Norfindel

    Active Member

    Mar 6, 2008
    235
    9
    Of course, everyone should wear eye protection when attempting something like this, or better yet: don't attempt it.

    In fact, the safest would be to wear eye protection always when working with electronics. One of the guys had a hot piece of tip42c package hitting his forehead at very high speed. Probably a mistake made the transistor to instantly smoke. If it had hit an eye, it could been serious.
     
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