HW problem: Teensy 3.6 stopped working, gets hot

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FrankSimon

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Hallo, I need help.
I am working with teensy 3.6 plus audio shield, using arduino/teensyduino plus audio-library on a windows 10 system, and until 60 minutes ago I was very happy doing funny audio-experiments on the signals coming from my fretless bass, passing through hard- and software back to my amp. (The pcb is powered by usb, no external supply, the bass is passive.)
Then, without any obvious reason, suddenly arduino said: "Teensy did not respond to a USB-based request to enter program mode. Please press the PROGRAM MODE BUTTON on your Teensy to upload your sketch." and nothing would work from this moment on.
Windows does no longer see the COM-Port. The LED does no longer light. There is a spot on the pcb very near to the micro-usb that becomes hot as soon as I put the usb plug in.
Can anyone help please?
The hardware is bought from the german distributor Eckstein and should be original. (I don't think I have to post my source code?!)
So long, Frank
 
A burning hot chip usually means the hardware as somehow been damaged or failed.

The first thing to try is disconnecting any other circuitry, so it's just the Teensy board. Then measure the 3.3V power with a voltmeter.
 
I have the same issue with a Teensy 4.1. Did you ever figure out what the problem was? Or how to fix it if possible?
 
No. I think it was electrostatic discharge. I never put things in the right housing. By now I lost 1 teensy and two audio boards. So be carefull.
 
Ok. Yeah i thought of that too however i am very carefull and always discharge before working on electronics.

Thank you for your reply though.
 
It could be simple over-voltage/over-current in an input triggering latch-up. You need to ensure anything external
connected to a low-voltage CMOS chips like these is unable to go out side the power supply voltage range.

Typically this is done with a resistor and a pair of schottky diodes. This will also catch electrostatic pulses.

The symptom of CMOS latchup is the whole chip suddenly drawing lots of current and getting very hot very quickly - you
must remove power ASAP to rescue it from frying. Its often triggered by too much current in an input protection diode,
hence the utility of external schottky diodes to bolster them.

Modern chips are supposed to be pretty resistant against this, but its a fundamental issue with CMOS structures on the
die being able to form parasitic BJTs which latchup like thyristors.

Even simple series resistors on inputs can protect effectively from many mishaps.
 
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