teensy4 no response

[jeffGao]

My teensy4 was normal before. However, after plugging and unplugging the USB once, the USB cannot be connected. There is no USB in teensyduino-> Tools-> Port. Teensy's USB interface and some chips are very hot, proving to be powered, and there are no signs of burnout from the outside. This USB cable was normal before, and replacing the USB cable did not work either.I pressed the teensy button, but no LED is lit.I am a beginner, please help me, thank you

macOS Catalina，Arduino1.8.10，Teensy Loader 1.48,Teensyduino_MacOS_Catalina

23 degrees Celsius at room temperature

Processor temperature 61 degrees Celsius

This chip is 97 degrees Celsius

 

[guzu]

Hi.
I seem to have the same problem.
You can find my post here.
Check if the GND and 3.3V rails are shorted. Mine seem to have 0 Ohm resistance between them.
If you find what is wrong, please let me know.

Thanks.

 

[jeffGao]

Hi.
The resistance between my GND and 3.3v is 0.4 ohms。

 

[KurtE]

Hopefully @Paul (and others) will have some ideas/suggestions. For what it is worth, so far I have not had any T4 die, except for one, I tried to use an earlier breakout board setup, which shorted out.

Normally when I first see postings about T4 not showing up in Serial port list, my initial suggestions would be, to try to reset board to default program (Hold program button for about 15 seconds until light comes on and then release). Or sometimes you can get it to program, by loading a blink sketch or like, do a verify command, then plug in your T4(or t3.x in similar way) while holding down the program button, and then either use Teensy program to program your Teensy or try doing the Arduino upload command... But since you are talking about it getting real hot I am guessing that this won't work.

It looks from the pictures above, like the board was unmodified... If you do a close inspection of both sides of the board, do you see any signs that maybe something shorted out.
Might help if you posted picture of back...

@guzu - did not see any pictures in your post or any clues. For example did you hook up the T4 to some other external device, that tried to use a lot more amperage than the T4's 3.3v regulator could supply. Example large RA8875 displays... Or a solder short, or hook up power to VIN, that was either too high a voltage or reversed...

Again hope you can resolve it.

 

[guzu]

If you do not have a short between the 3.3V and GND rails, you probably have a different issue with the board than mine. The reset option mentioned by KurtE could be useful to you.

@guzu - did not see any pictures in your post or any clues. For example did you hook up the T4 to some other external device, that tried to use a lot more amperage than the T4's 3.3v regulator could supply. Example large RA8875 displays... Or a solder short, or hook up power to VIN, that was either too high a voltage or reversed...

Again hope you can resolve it.

@KurtE - I use a PCB designed by me with the Teensy. I power a NRF24L01+ PA LNA module (13.5 mA), a MPU6050 module (3.9 mA), a HC-05 Bluetooth module (30mA), and a Teensy Audio Shield (not connected yet, but uses about 100mA) with the Teensy 4.0 (can sink 250mA on the 3.3V pin according to the forums). So the current should not be a problem...I think.

When I connect the USB cable to the Teensy 4.0 it makes a weak hissing sound for about 3 seconds then it stops. I think that is when the battery pack protection kicks in and cuts the power or the Teensy cuts the power to its self somehow. It does not get hot. So I cannot try the RESET option you suggested because the board does not stay on for 15 seconds.

There is no solder short because the PCB and the Teensy worked for a few weeks.
The power to the VIN pin comes from a AMS1117-5.0 voltage regulator that is fed power from a 9V battery. So I think this should not be a problem either.

Any help would be appreciated. Thanks.

 

[jeffGao]

Thank you for your help. my T4 did not have any hardware modification, just completed all the examples according to the tutorial on the official website. I have tried resetting the T4 board, but no LED will light up after pressing the button (actually it never lights up again after a failure), and I have carefully observed the T4 board from the appearance without any burnt or Traces of deformation. I don't know how to find the hardware failure, if you have any ideas can guide me to try.