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Thread: Burned out Teensy 3.6?

  1. #1
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    Burned out Teensy 3.6?

    I received some LED strips.. about 50 or so LED's in each strip. Everything was already soldered for me.. I used some jumper cables from my GND, 3.3V, DA1 pins to my LED strip and it ended up turning off when I connected them.

    Now my teensy wont get any data over the serial even if it's the blink program. Did I possibly brick it? I'm new to electrical engineering and was just messing around.

  2. #2
    Senior Member+ Theremingenieur's Avatar
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    Fail n 1.) A simple LED consumes between 15 and 30mA. 50 simple LEDs consume thus between 750 and 1500mA. RGB LEDs consume the triple. The Teensy Datasheet states clearly that the 3.3V pin can source not more than 250mA.

    Fail n 2.) LEDs stripes can not be driven from any DAC pin (which can not source more than 1mA). They need to be driven by PWM signals. There are specific libraries for that, included for free in your Teensyduino installation.

    Trash your roasted Teensy, RIP. Before buying a new one, I suggest you finish your electrical engineering studies first.

  3. #3
    Senior Member+ defragster's Avatar
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    Also - look into what 'some LED strips' are at hand. If they are similar to one on Adafruit or SparkFun there may be a more extensive tutorial on hooking them up - power requirements and what Digital Data pin to feed them the control signal with. Depending on what they are they need 5 Volt power - the PJRC Prop Shield may have been a guide - but would have needed external power as well.

  4. #4
    The Teensy 3.6 has a 500ma fuse. Perhaps you just blew the fuse.

    See https://www.pjrc.com/teensy/schematic.html for the schematic.

    A picture of the PCB can be viewed at https://www.pjrc.com/store/teensy36.html.

    The fuse is the part in the upper left corner of the picture. You can test by measuring the voltage into and out of the fuse. If 5 volts from the USB cable goes into the fuse and nothing appears on the other side then you probably found the issue.

    Of course you do not have an exact replacement fuse but you could jumper across the fuse with a very very fine piece of wire (roughly 40 gage wire or so -- just a fine fine fine strand of some stranded wire) -- then remove all connections except the USB cable and try flashing the blink program again.

  5. #5
    Senior Member PaulStoffregen's Avatar
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    Quote Originally Posted by e4x View Post
    Everything was already soldered for me.. I used some jumper cables from my GND, 3.3V, DA1 pins to my LED strip and it ended up turning off when I connected them.
    Was some other power source connected to the LEDs?

    If the LEDs had 5V power and you accidentally touched Teensy's 3.3V power to the 5V power from LED, that 5V power applied to the 3.3V pin would instantly destroy the Teensy.

    Teensy is designed to take 5V power at its VIN pin, or VUSB pin. It all depends on the details like exactly where the wires were connected, and what other sources of power were present. We can't see what you actually did... quite a lot of guesswork needed here.

  6. #6
    i keep the stuff i destroy in special spot of work area. helps me to remember how dumb i can be. plus, at some point i may be able to fix it, although have doubts about that. but that fuse tip might be worth looking into. i used to jump right in on stuff thinking devices were error tolerant, i fried a $160 minnowboard thinking it probably had over voltage protection which it did not. that's the star of my fail collection.

  7. #7
    Senior Member+ Theremingenieur's Avatar
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    I would never bridge a fuse without having made sure beforehand that all components in the following circuit are 100% intact! I find it highly irresponsible from drmartin to give such advice.

  8. #8
    Quote Originally Posted by Theremingenieur View Post
    I would never bridge a fuse without having made sure beforehand that all components in the following circuit are 100% intact! I find it highly irresponsible from drmartin to give such advice.
    I respect your comment but suggest that replacing a fuse with a fuse wire that will act as a replacement fuse is not totally unreasonable. I suggest we just let this tangent die.

  9. #9
    Senior Member+ defragster's Avatar
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    Quote Originally Posted by Theremingenieur View Post
    I would never bridge a fuse without having made sure beforehand that all components in the following circuit are 100% intact! ...
    Just to add, not prolong … but ( from my amateur reading - SparkFun has photos of similar part ) the fuse element is a PTC fuse that protects from over current ideally non destructively - when it cools it would naturally return to a functional state. If it doesn't then the extent of the over current was enough to take the part beyond design specs. Also in reading a bit the nature of the PTC is it turns the over current to heat - but doesn't stop all current flow to some degree {"...allow only a small leakage current"}.

    So a simple test of the PTC is called for - if it is blown then in failing it would seem it couldn't have worked well enough to keep the stuff downstream protected.

  10. #10
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    Quote Originally Posted by defragster View Post
    Just to add, not prolong … but ( from my amateur reading - SparkFun has photos of similar part ) the fuse element is a PTC fuse that protects from over current ideally non destructively - when it cools it would naturally return to a functional state. If it doesn't then the extent of the over current was enough to take the part beyond design specs. Also in reading a bit the nature of the PTC is it turns the over current to heat - but doesn't stop all current flow to some degree {"...allow only a small leakage current"}.

    So a simple test of the PTC is called for - if it is blown then in failing it would seem it couldn't have worked well enough to keep the stuff downstream protected.
    It's clear to me now!

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