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Thread: Replacing CPU on Teensy 3.0

  1. #1
    Junior Member
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    Replacing CPU on Teensy 3.0

    My Teensy 3.0 just released the "magic smoke". I may have accidentally pulled too much current from the 3.3v output or fed 5v into the same, in either case the CPU has a nice little brown bump on it. I am going to order a replacement CPU, remove the old CPU and solder in the new one. Is there anything I will need to do to get it working after I replace the CPU to program it, or will it just show up when I plug in the USB? (will I need to load a bootloader, etc?).

  2. #2
    Senior Member PaulStoffregen's Avatar
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    If the Mini54 survived, you should be able to put a blank MK20DX128VLH5 on the board and have it work.

    The USB serial number will come up as 4294967295, since the "write once" area comes initialized at 0xFF in every byte. Likewise, the Ethernet Mac number in write-once will be all 0xFF.

  3. #3
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    I hope so, I don't think I can easily replace the Mini54 For your enjoyment I have attached a picture of my poor CPU Click image for larger version. 

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  4. #4
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    Sweet it works!

  5. #5
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    First, wiltwong, let me congratulate you on your soldering skills. I can barely even see all those little wires, let alone attempt to solder them...

    But second, my teensy 3.1 failed in exactly this same way, with a pop, point source glow + smoke, followed by a bump in that same place.

    To help me figure out what I did wrong (and avoid it on the next teensy), does anyone know what type of error will result in the above behavior?

    Summary of what I'm doing is below, if that helps, but not really asking anyone to solve this for me. I just need some more info to help me investigate more.

    I had it plugged into an OctoWS2811 and was powering everything by supplying +5V and ground to those pins on the OctoWS2811.
    I can't find a link to the power supply i'm using but it is a 5v 25A in ATX form factor and i was using the +5V "standby" line for power and had not yet pulled the power-on pin low to spin up the main 5V rails (there is no +12V so i don't think the "overvoltage when not powering +12V" applies and i measured the voltage at 5.2V)

    I had connected it the exact same way several times before (and started the main +5V to power the LEDs, and ran a tweaked version of the Rainbow example).

    This time I had loaded the Fire example, but i didn't (directly) change anything related to any pins. My changes were:
    1. modify xy function for my 2-strand 10x10
    2. set ledsPerPin to 50 instead of calculating by width*height, since i'm only using two strands
    3. set width and height to 10.

    I did have the LEDs connected, but not (yet) powered. And no code to wait until the power comes on to try to send them data. It's not possible to burn the chip by trying to send data + ground to WS2811/2 LEDs without the +5V on the LEDs is it?

  6. #6
    Senior Member pictographer's Avatar
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    Don't know the exact failure mode in your case, but reversing power and ground will sure make the MK20DX128VLH5 heat up. (Not recommended!)

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