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Thread: Two Teensy 4.0 boards

  1. #1
    Member geekguy's Avatar
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    Two Teensy 4.0 boards

    Hi,

    I have been away for quite awhile but I am back! I just got my first two Teensy 4.0 boards from Adafruit, and I have Circuitpython one one.

    However, the second one is totally unresponsive. It acts like it is dead, but I do not understand how that can be. All the soldering looks good, and I just resoldered all the pins to be sure. It still acts like it is dead. I can not get any response from it and it will not allow me to load Circuitpython on it. I also can not access it from the Arduino 1.8.13 IDE with the latest Teensyduino (just downloaded) installed.

    Does anyone have an idea what else might be wrong? I got the other Teensy 4.0 working right away, so I am confident that this one should be working too.

    Now, neither one is working! This is very odd, especially since one has been working perfectly with Circuitpython. I am completely mystified!

    Update: I am using the Teensy Commandline loader v2.2

    8-Dale
    Last edited by geekguy; 04-16-2021 at 03:59 AM.

  2. #2
    Senior Member+ MichaelMeissner's Avatar
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    If the Teensy 4.0 is mostly dead, try holding down the programming pin for 15 seconds. This will cause the boot loader chip to reset the main chip and load a blink program. And obviously make sure you are using a USB cable that provides data. Charge only cables can't be used for programming, but sometimes it isn't obvious when a cable is charge only.

    If you've been soldering on the solder pads underneath the Teensy, it is easy to have an accidental solder bridge to one of the components underneath the Teensy.

  3. #3
    Member geekguy's Avatar
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    Quote Originally Posted by MichaelMeissner View Post
    If the Teensy 4.0 is mostly dead, try holding down the programming pin for 15 seconds. This will cause the boot loader chip to reset the main chip and load a blink program. And obviously make sure you are using a USB cable that provides data. Charge only cables can't be used for programming, but sometimes it isn't obvious when a cable is charge only.
    I just did this with one Teensy 4.0, but it still does not respond to attempts to program it. I have good USB data cables.

    Quote Originally Posted by MichaelMeissner View Post
    If you've been soldering on the solder pads underneath the Teensy, it is easy to have an accidental solder bridge to one of the components underneath the Teensy.
    I have not soldered to anything on the underside of either of my Teensy 4.0 boards.

    8-Dale

  4. #4
    Senior Member+ defragster's Avatar
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    @geekguy: Did the 15 second Restore proceed as > Button held 15 seconds to RED LED flash, Button release, some ~30 seconds of RED LED on, then T_4.0 return to 1 second Blink?
    > It won't have active USB at that point - but with Teensy Loader open a Button press should see it active in bootloader mode.

    That would indicate some base level of function, or not.

    Closely comparing the two boards are all components present and similarly aligned on both boards top and bottom? Any signs of excess solder or splatter on any of the components?

    Is it to post a clear photo showing silkscreen and componnets?

  5. #5
    Member geekguy's Avatar
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    Quote Originally Posted by defragster View Post
    @geekguy: Did the 15 second Restore proceed as > Button held 15 seconds to RED LED flash, Button release, some ~30 seconds of RED LED on, then T_4.0 return to 1 second Blink?
    There is no activity at all on the Teensy 4.0. No flashing or blinking red LED at all. Both just seem to be "dead" now.

    Quote Originally Posted by defragster View Post
    Closely comparing the two boards are all components present and similarly aligned on both boards top and bottom? Any signs of excess solder or splatter on any of the components?
    Everything looks good to me. No solder splashes, which would be easy to see. No solder bridges, etc. I can not see anything that physical that may cause a problem. I even rebooted my computer without

    Quote Originally Posted by defragster View Post
    Is it to post a clear photo showing silkscreen and componnets?
    Click image for larger version. 

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    8-Dale

  6. #6
    Senior Member PaulStoffregen's Avatar
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    If it's completely unresponsive, let's first look at whether it's getting power....

    Try using a DC voltmeter to measure VIN-GND (should be about 5V) and 3.3V-GND (should be 3.3V).

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    Member geekguy's Avatar
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    Quote Originally Posted by PaulStoffregen View Post
    Try using a DC voltmeter to measure VIN-GND (should be about 5V) and 3.3V-GND (should be 3.3V).
    Teensy 4.0 #1: It looks like I do not have 3V power. I have 5.08V.
    Teensy 4.0 #2: I do not have 3V power. I have 5.08V.

    I do not understand this at all. One of my boards was working for awhile, but the other never worked.

    8-Dale

  8. #8
    Senior Member PaulStoffregen's Avatar
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    I'm a bit confused, trying to parse this

    Teensy 4.0 #1: It looks like I do not have 3V power. I have 5.08V.
    Teensy 4.0 #2: I do not have 3V power. I have 5.08V.
    Neither board has 3V power? Or one does and the other does not?

  9. #9
    Member geekguy's Avatar
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    Hi, Paul

    Both boards have the same results - no 3V power, but 5V power at 5.08V.

    8-Dale

  10. #10
    Member geekguy's Avatar
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    I have been thinking more about this. It seems strange that two Teensy 4.0 boards from the same vender would have the same exact failure.

    8-Dale

  11. #11
    Senior Member+ defragster's Avatar
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    The one board worked for some time it seems - but the other never did?

    It is strange to have two boards go bad.

    Boards have distributors. All boards are manufactured and tested and packaged through/by PJRC.

  12. #12
    Member geekguy's Avatar
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    Quote Originally Posted by defragster View Post
    The one board worked for some time it seems - but the other never did?
    Yes.

    Quote Originally Posted by defragster View Post
    It is strange to have two boards go bad.
    With the same exact failure.

    Quote Originally Posted by defragster View Post
    Boards have distributors. All boards are manufactured and tested and packaged through/by PJRC.
    I understand that. I am not questioning PJRC. There are ways boards can be negatively affected, even in transportation between manufacturer and dstributor.

    8-Dale

  13. #13
    Senior Member PaulStoffregen's Avatar
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    I'd really like to know what went wrong.

    If you're willing to measure more voltages, on the bottom side are 4 small round test pads, located between the rectangle pads for pins 24-33. Can you measure those 4 voltages (keeping the negative lead on GND)?

  14. #14
    Member geekguy's Avatar
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    Quote Originally Posted by PaulStoffregen View Post
    I'd really like to know what went wrong.
    So would I.

    Quote Originally Posted by PaulStoffregen View Post
    If you're willing to measure more voltages, on the bottom side are 4 small round test pads, located between the rectangle pads for pins 24-33. Can you measure those 4 voltages (keeping the negative lead on GND)?
    I have 0V on all four pins on both modules. I did not believe this until I took three sets of readings. I wish I had a known good module to compare with.

    8-Dale

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    do you have high definition pictures of both sides of the PCB of both boards?

  16. #16
    Senior Member+ defragster's Avatar
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    Was either one powered to see blink before soldering? Other than soldering was either ever connected to anything except the USB cable? Wires or breadboard to anything?

    Did the first bad one Never take any code upload?

    The other had some short signs of life and ran "Circuitpython" - any other Arduino sketches successfully loaded to test?

    As noted before the only Teensy I've had die was due to overclocking without a heat sink - that shorted out the 1062 chip.

  17. #17
    Senior Member PaulStoffregen's Avatar
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    Quote Originally Posted by geekguy View Post
    I have 0V on all four pins on both modules.
    Sounds like hardware failure.

    I really want to figure out what happened here. I've asked Robin to contact you next week.

  18. #18
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    Quote Originally Posted by tonton81 View Post
    do you have high definition pictures of both sides of the PCB of both boards?
    I only have what I have already posted - pictures taken with my phone.

    8-Dale

  19. #19
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    Quote Originally Posted by defragster View Post
    Was either one powered to see blink before soldering? Other than soldering was either ever connected to anything except the USB cable? Wires or breadboard to anything?
    I did not power the boards before soldering pins to them. From now on, I will. This is the first problem I have had that I could not trace to something I did.

    Quote Originally Posted by defragster View Post
    Did the first bad one Never take any code upload?
    I was able to load Circuitpython and Arduino on board #1 and it ran for a little while before it failed. I was never able to load Circuitpython or anything else to board #2.

    Quote Originally Posted by defragster View Post
    The other had some short signs of life and ran "Circuitpython" - any other Arduino sketches successfully loaded to test?
    I installed the latest Teensyduino and loaded a blink sketch to #1 and that worked. Then I loaded Circuitpython and it worked for awhile before failure.

    Quote Originally Posted by defragster View Post
    As noted before the only Teensy I've had die was due to overclocking without a heat sink - that shorted out the 1062 chip.
    I do not overclock my MCUs because that can cause failures.

    UPDATE: I did plug both boards into a breadboard after I soldered pins to them,

    8-Dale
    Last edited by geekguy; 04-18-2021 at 03:13 PM. Reason: Added detail

  20. #20
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    Quote Originally Posted by PaulStoffregen View Post
    I really want to figure out what happened here. I've asked Robin to contact you next week.
    I would like to know what happened too. OK, great.

    8-Dale

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    is it possible the voltage at the usb is unstable? are you powering from VIN? There used to be old Alpha power supplies that would fry computer parts.. 😆

  22. #22
    Member geekguy's Avatar
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    Quote Originally Posted by tonton81 View Post
    is it possible the voltage at the usb is unstable? are you powering from VIN? There used to be old Alpha power supplies that would fry computer parts.. 
    I do not think so. I had both boards connected to a powered USB hub. Everything else on that hub works fine.

    8-Dale

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