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Thread: Teensy 4.0 3.3v shorted to ground

  1. #1
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    Teensy 4.0 3.3v shorted to ground

    Hi as stated in the title my new Teensy has continuity from ground to 3v pin. It has become non responsive when powered via USB cable. Measuring 3v pin with a Dmm shows no power.

    I was able to flash the teensy using teensy loader. After that I noticed the led on teensy flashing 4 times then pausing and repeating.

    I thought the flash had not worked so plugged it back into the computer only to find it was non response and the MCU was getting warm after some time. Thatís when I started testing the pins with a Dmm and found the short.

    Is the teensy dead or can it e revived? I have tried the 15 sec reset to no avail.

  2. #2
    Senior Member+ defragster's Avatar
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    Was it seen blinking when first powered up?
    Were any successful uploads seen to work?
    Anything soldered or connected?

  3. #3
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    It was blinking when first powered on.
    I was able to erase and upload a hex file
    Pins soldered to the Teensy to seat in sockets.

  4. #4
    Senior Member+ defragster's Avatar
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    With soldering there could be a short or other 'changes' made to the Teensy.
    Examine each solder point for clean soldering without excess or short to anything else. DMM can be used to check all adjacent pins for shorts. Confirm nothing splattered to other components, or any got shifted or removed. Posting a clear photo can allow others here to see as well.

  5. #5
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    I have checked with a jewellers lupe and can't see any defects with errant solder.

    Click image for larger version. 

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    Click image for larger version. 

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    Detecting shorts between: 3v and GND, Pin 17 & 19
    Last edited by Rumble; 01-09-2023 at 06:51 AM. Reason: additional info

  6. #6
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    U4 the TLV75733P has 4.8v on its input but only .5v on its output. Is it worth replacing it?

  7. #7
    Senior Member+ defragster's Avatar
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    Not an EE ... Having a short between "Pin 17 & 19" suggests something else went wrong?

    There may be further damage? The TLV75733P went bad and may have taken stuff with it, or something went wrong and took the TLV75733P with it?

    Nice pictures by the way - indeed solder and parts look clean and properly placed as seen here.

  8. #8
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    It's dead. I ordered a new one.

  9. #9
    Senior Member+ defragster's Avatar
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    Good luck. Make sure to keep 5V away from all pins not 5V or VUSB. Even a touch can break the 3.3V hardware. Not sure if that could explain the loss.

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