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HELP! What the heck happened here?

Discussion in 'Cinestar 8' started by Ben Freedman, Feb 4, 2013.

  1. Howard Dapp

    Howard Dapp Active Member

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    Glad you discovered that a trace was the issue.

    On another note, exposed electronics terrify me! I see motor wire B is a little frayed. One of those little frays jump loose then shorten between two legs on the ATMega..not good! In fact I see all sorts of dust dirt and debris on the controllers. Scary for me
     
  2. Ben Freedman

    Ben Freedman Member

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    Hey, Howard....

    Sorry for the confusion. If you read my email, the trace was NOT the issue. That was on BL3, and the overheat was on BL4. I wish it was just a broken trace, but I am still in the dark as to what caused BL4 to overheat...

    Ben
     
  3. Howard Dapp

    Howard Dapp Active Member

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    Sorry for the confusion Ben.

    This machine flew problem free in the past? I would say check your solders also pull the esc and look it over very closely, maybe with a loupe, check for any foreign material and check the cap legs.
     
  4. Ben Freedman

    Ben Freedman Member

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    I'm currently replacing the BL with another from a defective PWD. We'll see if that fixes the problem. Also replacing the one with the broken trace. Keep in mind these birds fly with no protection on the electronics at all, so they must be able to resist a little dust and debris from the outside world.

    I've had 10 or so perfectly normal flights on this C8 so far....

    Best,

    Ben
     
  5. Howard Dapp

    Howard Dapp Active Member

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    Great keep us posted. It's not so much the dirt I would be concerned with but moisture or any fine bits of metal from anything. Been building and flying these things for years and have experienced it all:) Give those things a good conformal coating. Just think about every piece of expensive electronic gear you own..what do they all have in common? No exposed electronics:)
     
  6. Shaun Stanton

    Shaun Stanton Active Member

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    Echoing Howard, looking at your picture I see that your blue wire is a little exposed with some freying and is awfully close to the red wire it is possible that those exposed freys could have caused an electrical arc over to the red wire, causing a partial short circuit under high current loads. I noticed that the solder joint looked dull as well. That could be an indication that it is a cold solder joint. If you had an intermittent short going while putting that BL under load that would explain the smoke. I would echo Josh on the Caps. If you theoretically had an intermittent short in your system the electrolytic material in the caps would have caused a reaction from the disruptive electron flow. They blow up and and smoke, and that would be my guess where the smoke came from. I would take a look at your entire PDB and see if you have any more wires that are either frayed or dull. You might have gotten away with it on your first 10 flights but as the board is being exposed to vibration and changes in temperature, could have caused that wire to vibrate close enough to cause an arc as well.

    My EE undergrad days I seen many Caps on some of my circuit boards start smoking and pop because I had them reversed or something shorted out:).
     
  7. Bo Tornvig

    Bo Tornvig Member

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    Not that I´m superstitious - but I fried BL4 yesterday... Could be a rain drop...
     
  8. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Sorry to hear that Bo.
    Out of curiosity, did you apply a layer of spray on conformal coating? If you did not, you might want to consider doing that.
    See http://rathergoodguides.com/documentguides.html --- the first document might be helpful.

    Andy.
     
  9. Bo Tornvig

    Bo Tornvig Member

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    Hi Andy,

    Thanks.

    I got it :)

    Ill spray all the boards tomorrow. Scary to see the bird loosing a wing...

    Bo
     
  10. Patrick Weeden

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  11. Zach Beggs

    Zach Beggs Member

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    Thanks so much Andy for this -- I had no idea until I was trolling the forums that moisture would be a problem.
     

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