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  1. #1
    Join Date
    9th August 2009
    Location
    Blacksburg, Virginia
    Posts
    738

    Eggfinder mini overheating?

    I recently built an eggfinder mini and tested it to be working quite well. I took it out of my rocket box a couple months later to show a friend and, while it wouldn't power up, it got hot. I mean too-hot-to-touch on the center pin of the GPS module and the diode at the power point. Has this happened to anyone? There doesn't appear to be any physical damage or change since it was working, and the battery connection and everything is identical. Is there a logical place to start looking, or test points I should check to see if something is straight-up fried?

    Jordan
    TRA Level 3
    NRVR

  2. #2
    Join Date
    22nd January 2017
    Location
    North Florida
    Posts
    46
    What type of battery are you using?

    -Dave
    -----------------------
    NAR# 103244
    Level 1 - PML AMRAAM 2
    Level 2 - Madcow Adventurer 3

  3. #3
    Join Date
    18th March 2009
    Location
    Wisconsin
    Posts
    3,761
    Do you have a short somewhere? A soldier bridge of something like that?


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    Mark Koelsch
    Tripoli 6155 L3
    Owner of http://www.rocketryfiles.com/
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  4. #4
    Join Date
    26th November 2009
    Posts
    5,214
    Not good. I had a "bad"Quantum I suspect a bridge under the Wifi chip so it resides in the junk drawer. The VR chip got super hot. Kurt

  5. #5
    Join Date
    3rd February 2012
    Location
    So Cal (ROC, TRASD, SCRA)
    Posts
    2,659
    Chances are that you got a solder bridge somewhere, possibly under the RF module. That's why I put a step in the assembly instructions to put a piece of paper masking tape under the RF module and trim it to the edges. If it's a dead short between power and ground, the Mini "will" work, but it's going to suck a lot of power out of the battery, possibly overloading the regulator. Worst case, that can lead to a regulator failure, which might send the full battery voltage to your GPS and RF modules. That's a bad thing... they will fry for sure. I would recommend carefully unsoldering the RF module and looking for anything that might be causing a problem.

  6. #6
    Join Date
    9th August 2009
    Location
    Blacksburg, Virginia
    Posts
    738
    Thanks for the replies - I've been afk for a bit due to work. I've also just gotten a new multimeter (the old one died) and will be be able to check some test points. Battery is a 2s lipo, good voltage on both cells with two testers, that isn't overheating or appearing to have any other issue.

    I will double check the RF module. I think I may have subbed Kapton tape for the masking under the RF module as I was concerned about long term stability of masking tape, but that shouldn't be the problem.

    The thing that's bugging me is that it managed to checkout fine after assembly. I even set it on my deck and drove around the neighborhood to see what kind of range I could expect and how it compared to my 70cm GPS unit. I've been trying to think what could have caused a good unit to go short and all I can think is that shrink-wrapping the battery to the board might have compressed something.

    Hopefully I'll get to do a checkout this weekend and will report back if I find where it went of the rails. Thanks again!

    Jordan
    TRA Level 3
    NRVR

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