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jomac
02-23-2014, 01:07 AM
I was in the process of writing some code for the Teensy 3.1. I had left the Teensy running since the night before running some code that showed elapsed time in seconds on a 16 X 2 LCD. The Teensy was running from an external supply with the recommended mods but hooked up to the PC via the USB lead, a set up i had used for a few days, nothing else was connected apart from the LCD.

I was ready to upload the code and looked at the LCD which now had a row of black squares on the first line, yet a few minutes before it was happily counting away. Pressing the reset had no effect so i disconnected the USB and noticed i didnt get the USB disconnect sound. I discovered the PSU light was a little dim and i measured the supply voltage which was now 3.66 volts instead of 5v, disconnecting the Teensy allowed the supply to rise to 5v. It was then that i noticed that the CPU was running very hot, too hot to leave your finger on. Disconnecting everything and leaving just the supply connected had no effect.

Im usually pretty careful will all precautions including static, but i cant understand whats killed this board, any idea's, and is it worth contacting the supplier?

John

bloodline
02-23-2014, 12:33 PM
I have been abusing a single Teensy 3.1 for a couple of month now, without taking more than sensible precautions (as I want to see how hard I can push it before it breaks). I might just be lucky, but the Teensy 3.1 has proven to be a robust little thing!

Paul seems really proactive on boards that fail mysteriously, best bet will be to contact him directly and see what he can do to help :-)


-Edit- I always include a little "Blinky" code in my sketches that toggles pin 13 periodically (usually using an IntervalTimer), that lets me know if the board is definitely working. Try uploading a simple blinky sketch just to confirm the board is dead. I use a Mac so I can easily see the USB connections in the System Profile... I assume you are using Windows, there must be something similar.

jomac
02-23-2014, 02:57 PM
Hi,
Thanks for the reply, trust me..its dead..!!

When applying external 5v power which is current limited to 500ma to the Teensy, it drags the voltage down to 3.66v and draws around the 500ma. At the same time, the CPU chip gets extremely hot, too hot to leave your finger on it. Whilst powered up, there is no life when the USB lead is connected, no longer seen by USB.

John

PaulStoffregen
02-25-2014, 09:50 PM
Usually only 2 things cause this kind of failure, applying too much voltage, or reverse polarity power on the 3.3V line.

You mentioned an adjustable current limit, which sounds like a lab bench power supply. It seems unlikely such a supply would misbehave badly.

I just can't know what happened here. But I can tell you the one thing which kills Teensy3 in this way is overvoltage, either a temporary spike or a supply with too much voltage.

jomac
02-26-2014, 02:20 PM
What would be the postage costs in sending a replacement programmed chip to the UK Paul?

jomac
02-26-2014, 09:13 PM
Hi Paul,
Ive been trying to send you a pretty urgent email, but it seems your inbox is full and wont accept any more

stevech
02-26-2014, 09:50 PM
ah, try sending it to the real boss, Robin.

jomac
02-26-2014, 10:16 PM
Ahhh...Who is that?