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Thread: Another dead Teensy?

  1. #1
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    Another dead Teensy?

    Hi,

    I think I killed my 2nd Teensy yesterday.

    I soldered the Audio shield underneath. At that time it still works.

    Click image for larger version. 

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    Then I solder the Teensy into a stripboard where `I had already soldered s bunch of buttons and connected for future componnets. Now it it wont start.

    I debugged things with my n00b knowledge and only weird thing is that when I connect my multimeter in contionious mode, I get a value of 1.5 of 0.5 (depending on which probe I put where) between the VIN pin and the GND pin. A fresh Teensy just reports 1 always when I do that.

    Any ideas as to what I did wrong? 2nd Teensy I ruined without really knowing what I did wrong I'm afraid it will happen again and again... Could it be the I solder too hot? Touch the pins for too long?

    help much appreciated

    Jeroen

  2. #2
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    I'm pretty sure I can see a solder short in the third image, one of the top pin row has a little blip
    of solder over the horizontal bus trace?

  3. #3
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    You mean this?
    If you mean the the thick lump first column where it says "276" then yes that is intentional. This is where the Teensy VIN gets its power from the 5V rail.

    Click image for larger version. 

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    WIP fritzing... (please note the perfboard is upside down in the schema)

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    I tried with a knife to separate all suspicious pads/points yesterday..

    So if it is indeed a short circuit, would that have killed the teensy or just prevent it from being powered?

  4. #4
    Senior Member+ KurtE's Avatar
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    Hello Jeroen,

    Hard to say yet what is going on.

    What happens when there is a short often depends on what is shorted. For example if VIN/GND shorted directly then no power goes to teensy, and it would likely survive, but not sure about the Adafruit board...

    Typically what I will do, when I solder up something like this, I will do a couple of quick checks, before I apply power. I usually start off, by getting out my old multimeter and check the resistance values, between things like: VIN to GND, VUSB to GND, 3.3v to GND, 3.3v to VIN... If any of these are zero or near zero, than likely I have some form of short...

    I ran into this just yesterday. I modified a board that I did a quick design of and Robotshop assembled for me (and a few others). I found I specified the wrong connectors for the QWIIC connectors. I specified the ones that you plug in from the top, but I actually designed for the ones that plug in from the side... And the two are not interchangeable. So the signals were reversed. I happen to have a few of right connections and replaced them... But before I plugged in the Teensy, I checked like I mentioned and found I had shorted 3.3v to GND... Which I then fixed...

    Now if that quick test does not show anything obviously wrong, next thing up is to plug it in and then test the voltages. Do you get 5v at the VIN pin?
    Your fritze picture is unclear to me where you are connecting up the +5v and GND from the Adafruit board. It looks like in your picture you are trying to connect it directly to the USB connector? I would expect that you would connect them up to the VIN pin (Top left pin) or maybe VUSB (probably not) if later you cut the VIN/VUSB connection such that the power from USB port does not connect directly to the output of the Adafruit board...

    But again my 2nd test would be to check the voltage at VIN... Alternatively, with multimeter what is the resistance from VIN of Teensy to the +5v pin of Adafruit board. Likewise from GND to GND.

  5. #5
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    hi Kurt,

    I've not soldered the Adafruit booster yet. I just connected its the 5V and G with crocodile clip cables to the 5V and GND strips in the middle of the board. They in turn are connected to Teensy VIN and Teensy GND.

    .. I don't power via USB, I cut those pads on the teensy.


    Good tips and I did test (although too late) and now teensy 5V tot teensy GND shows a resistor value of 0.5. That should just be 1, right??

    I'll try to do the

  6. #6
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    Building version one I would put female headers on the stripboard for the adudioboard, and male/female pass through headers on the audioboard. Then connections can be checked without any board, with one and then finally two boards.

    When it all works, make a more compact soldered version, or keep the headers for flexibility and maintainability.

  7. #7
    Senior Member+ defragster's Avatar
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    T_3.2 right?

    IIRC - there was a note recently about an aggressive "cut those pads on the teensy" can penetrate too deep and sever a needed power connection on the next layer.

    Though post #1 suggests it was working after that when it was soldered to Audio board? - so that may not apply unless it was nearly cut and failed after?

    ... that thread was weeks back so not sure of diagnosing that ... it seems the 5V pin connect to the next inline component ... the Fuse end? needed to be checked it was getting connected/power.

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    Teensy 3.2 yeah. It was working after cutting the pads and soldering the audio shield. I happened after soldering the teensy to the perfboard.


    I've never tried a solder sucker, but I ordered one and will try to remove solder joints one by one and see if it comes back to life

  9. #9
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    Omg, it's alive!!

    Thanks for all the tips, especially @MarkT and @KurtE . I measured the voltage at the adafruit booster's end, that said 5.2V. But on the perfboard rails there was only 0.2 or so... Sometimes 0.
    Then I desoldered two suspicious looking joints. That solder sucker thing works great!. Then I had 5.2 on the rails, but none on the Teensy.

    After soldering the rails G to teensy G again, Teensy turned on.

    Have to do some more checks to see if the audio board is also fine, but think it will be.

    J

  10. #10
    Senior Member+ KurtE's Avatar
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    Glad it is looking promising!

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