Hello guys, I have a problem that my Teensy 3.2 stopped working and now I checked and the VUSB pin is shorted with the AGND pin. I was doing some test to try the ADC my Teensy is brand new please help me out I tried one simple test to use the ADC with 16 bits, I was using a simple 1K potentiometer to variate a 5V signal and read it with A0 and it worked fine. After this I removed the potentiometer I was working on another circuit to test another sensor and when I tried to load read the serial port it didnt work. Now I tried to load the basic blink program and it doesn't work either. I noticed the teensy is heating up every time i plug the USB cable but only near the usb port so I guess the regulator is the one with the problem. I cut the trace that connects VUSB with VIN and now when I plug the USB cable the board is fine but I give the external power of 5V and the board heats up inmediately. Finally I checked the pins with the multimeter and the VUSB and AGND are shorted. Is there anything I can do to fix this problem. I am extremely dissapointed because like I told you before this board is BRAND NEW! and after the second test it cannot work anymore, can I apply to some warranty or something. Plus I need this board for a very important project and if a order a new one it might be too late until it arrives to my place. Please help me out with this one.
VUSB and AGND are shorted. Teensy Heating up and not working
- Thread starter drfutter
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Theremingenieur
Senior Member+
1.) Never buy only one board, especially when starting a project, buy them by packages of at least 3 
2.) Never apply voltages > 3.3V on analog inputs. Only the digital inputs are really 5V tolerant
2.) Never apply voltages > 3.3V on analog inputs. Only the digital inputs are really 5V tolerant
Constantin
Well-known member
It's likely fried. My guess is that your 5V power supply may have drifted much higher than 5V when it was unloaded and then cooked the inside of the Teensy. So even if you used a digital / analog capable pin, the design goal should always be to use a maximum input voltage of 3.3V or whatever you're setting with AREF. If you go above that voltage (i.e. 3.4V on a stock Teensy, for example), all the ADC will report is 3.3V while the protection diodes get a workout.
Be nice to your Teensy! :-D
Be nice to your Teensy! :-D
vitormhenrique
Well-known member
post some high resolution pictures...
Teensy don't magically short itself, either you connected 5v to a 3.3V pin or you messed something up while soldering, or applied an incorrect input voltage...
Teensy don't magically short itself, either you connected 5v to a 3.3V pin or you messed something up while soldering, or applied an incorrect input voltage...
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PaulStoffregen
Well-known member
Get a bright light and a magnifier, so you can inspect the Teensy carefully. I'm sure with magnification, you'll be able to see the short.
Every Teensy is fully tested here. A short like this couldn't get through the tests. It's almost certainly a solder bridge or wire touching somewhere on the Teensy. Look carefully and I'm sure you'll find it.
Warranty replacement for hobbyist & DIY electronics is a difficult matter. Generally, if your Teensy doesn't work, you need to report the problem promptly, and before soldering or connecting it to other stuff that would be likely to cause damage. The point is warranty replacement is about fixing PJRC's mistakes. If we soldered the board wrong, or we used a wrong part, or packaged it badly, or did something else that caused the trouble, then of course PJRC should replace it. But warranty is not an insurance policy covering accidental damage that happens to a Teensy that was in good condition when received. The reality of DIY electronics is wiring mistakes and other "learning experiences" that damage parts are pretty common. Robin and I try to be reasonable and evaluate each case. We do understand there are some types of problems which can't become evident until stuff is connected, which is why we evaluate on a case by case basis.
But in a case like this, and especially if soldering was done, PJRC's usual position is you need to report a problem like a VUSB-AGND short *before* you connect anything else to Teensy. If we really did make a manufacturing mistake, and it somehow got through both the bed-of-nails test to all the pins and the USB+LED programming test, it would have been immediately obvious the moment Teensy was first plugged in.
Every Teensy is fully tested here. A short like this couldn't get through the tests. It's almost certainly a solder bridge or wire touching somewhere on the Teensy. Look carefully and I'm sure you'll find it.
Warranty replacement for hobbyist & DIY electronics is a difficult matter. Generally, if your Teensy doesn't work, you need to report the problem promptly, and before soldering or connecting it to other stuff that would be likely to cause damage. The point is warranty replacement is about fixing PJRC's mistakes. If we soldered the board wrong, or we used a wrong part, or packaged it badly, or did something else that caused the trouble, then of course PJRC should replace it. But warranty is not an insurance policy covering accidental damage that happens to a Teensy that was in good condition when received. The reality of DIY electronics is wiring mistakes and other "learning experiences" that damage parts are pretty common. Robin and I try to be reasonable and evaluate each case. We do understand there are some types of problems which can't become evident until stuff is connected, which is why we evaluate on a case by case basis.
But in a case like this, and especially if soldering was done, PJRC's usual position is you need to report a problem like a VUSB-AGND short *before* you connect anything else to Teensy. If we really did make a manufacturing mistake, and it somehow got through both the bed-of-nails test to all the pins and the USB+LED programming test, it would have been immediately obvious the moment Teensy was first plugged in.
According to the OP, it worked at first, the shorted condition happened later after changing some connections. So it doesn't sound like a manufacturing defect.
Thank you guys for the quick responses.
So, if I understand correctly the analog input pins all work at 3.3V and will report that as maximum even when 5V is applied right?. Now My question is there any posibility to read differential analog signals using the Teensy? I will be reading from a sensor which outputs is +-5V, so is this possible, what hardware and software changes do I have to make to make this work.
Dear Paul I understand what you mean, my point about the warranty question is because the Teensy was working and it stopped working out of the blue. Maybe some spike from the supply like the people here said might have caused the failure. I am going to buy 2 new ones. However I am still a little concern that this board is really easy to be damaged, that is all. Thank you for your reply also. PD. just FYI I never said anything was soldered to the board.
So, if I understand correctly the analog input pins all work at 3.3V and will report that as maximum even when 5V is applied right?. Now My question is there any posibility to read differential analog signals using the Teensy? I will be reading from a sensor which outputs is +-5V, so is this possible, what hardware and software changes do I have to make to make this work.
Dear Paul I understand what you mean, my point about the warranty question is because the Teensy was working and it stopped working out of the blue. Maybe some spike from the supply like the people here said might have caused the failure. I am going to buy 2 new ones. However I am still a little concern that this board is really easy to be damaged, that is all. Thank you for your reply also. PD. just FYI I never said anything was soldered to the board.
PaulStoffregen
Well-known member
No, you can't directly measure negative voltage with Teensy. If you drive any pin more than about -0.3V below ground, you risk damage to the chip.
To measure negative voltage, you need to build some sort of circuit which translates the voltage into the range Teensy's pins can handle. I highly recommend testing the circuitry with a voltmeter before you connect its output to Teensy!
Here's an article I wrote about a very cheap way.
http://dorkbotpdx.org/blog/paul/control_voltage_cv_to_analog_input_pin
Much better, but more complex ways exist. Follow the link in that article to a conversation about those other ways.
Whatever you do, test with a voltmeter and make sure its output stays within the legal range before you connect it to Teensy!
Yes, you can use a resistor divider. Fixed resistors, to avoid accidents.
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