Identify a cap..

Discussion in 'General Electronics Chat' started by bob332, Apr 12, 2011.

  1. bob332

    Thread Starter Member

    Feb 14, 2011
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    well, it has been quite a bit of time, but i let the magic smoke out :(

    could i please get some assistance identifying the cap in this pic that is circle by red & blue:

    [​IMG]

    also, i am assuming i plugged the power in backwards (guess i should have triple checked, as i double checked :(), so would the cap be the sacrificial lamb, or could the power still take out other items?

    thanks,
    bob
     
  2. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    It looks like a 47 uF tantalum. It's tantalum from appearance, but also because the positive end is marked, not the negative end as with aluminum electrolytics.

    Be sure there s no sort at B. It is very close.

    John
     
  3. bob332

    Thread Starter Member

    Feb 14, 2011
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    thanks for the info. that was a pic i found off the internet, i do not have the jumpers on mine, but the cap was burnt through, completely unrecognizeable. do you think other items could have been destroyed because of this? it is for a radio controlled model, so if anything else could have been affected, please let me know. power was from from 4 x 2200mA AAA cells
     
  4. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    Now I see the servo pin outs with center positive. Sure other things could be messed up. Your chance of fixing one of the big IC's is nil. I would replace the capacitor, and see if it works. If it doesn't, check the voltage at the output of what is probably the voltage regulator (top, labeled 6Z X6). That is kind of the next line in the sequence.

    I suspect the capacitor is mostly to smooth out glitches in the supply voltage. If it died open (or after you remove it), you might see if the device (receiver?) works at all.

    John
     
  5. bob332

    Thread Starter Member

    Feb 14, 2011
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    when i powered the 5V line, other items that were connected to the 5V line, their leds went dim. i will remove it and connect power and see how it goes.

    is it normal for a cap to burn to the point of nearly having a whole in it? it melted part of the plastic housing it was in. i will take a pic tomorrow.

    thanks for the info :)
     
  6. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    Tantalums will explode if voltage is reversed to them. It can be spectacular.

    The problem I see is that if simple things don't work (I am not optimisitc), you could spend a lot of time trouble shooting the radio, find the problem, and still not be able to fix it, because the parts will not be available.

    John
     
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