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Topic: Arduino Nano and short circuits (Read 3 times) previous topic - next topic

jet

In the past ~3 years, I've done a number of projects using Arduino of various kinds and helped in a few classes where many students were using Arduino for the first time and I've only seen one or two Arduino boards killed by a temporary short.

In the past month, I've fried two Nano v3.0 with brief shorts due to a loose wire.   Each time, the same SMT component smoked:
http://www.flickr.com/photos/allartburns/4225076075/

Are the Nano V3's especially fragile, or am I just unlucky?

retrolefty

Quote
Are the Nano V3's especially fragile, or am I just unlucky?


I would say it looks like the Nano is a more fragile design. The standard Arduino board uses a thermofuse to limit current from the USB port to 500ma and resets automaticaly when the short is removed. On the Nano there doesn't appear to be a thermofuse installed. The burned component looks to me to be the D1 isolation diode. It's used to 'switch' the +5vdc source from either the USB power source or the on-board +5vdc regulator and allows whatever source has the higher voltage to supply the boards current. The parts list shows it as a 500ma diode, so most likely a careless wire could cause a short circuit and is burning the diode open.
Just a guess as I don't have the Eagle program installed to actually see if that component is D1 or not.

Lefty

jet

Thanks -- I was trying to decipher the Eagle pcb layout and getting nowhere.

So in there, I should be able to replace this with an SMT rework station and a steady hand?  I picked up a cheap refurb lately, this seems like a good thing to practice on.

Gravitech

#3
Jan 03, 2010, 01:26 pm Last Edit: Jan 03, 2010, 01:26 pm by coolguy Reason: 1
Or better yet, just contact us to get a RMA# and you can send them back for a free repair! support@gravitech.us

Happy Nano!

drh

Is Gravitech the manufacturer of the Nanos? I've fried a couple as well and would like to be able to return them for repair.

Funman1

See here for my repair
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1256229321

cr0sh

The best way to prevent this (but not eliminate) is to not apply power to the circuit while you are building it. If you are probing with a meter or scope, do it carefully so as not to cause wires to become loose; there shouldn't be any loose or single-ended wires near a project while power is applied.

Finally, if probing, do your best to do so "one handed"; this gets you used to this method, so that in the future if you are working on a project with a high-voltage component, or line voltage, you don't have any way to make a conductive path across your heart via the hands holding the probes.

Learning to operate the circuit without having single-ended wires floating around, or working on the circuit "live" will also help keep you alive when it comes to working with line-level circuitry or high voltage.

For obvious reasons as can be seen from the above, though, you shouldn't probe your circuits "live"; hook the probes up where they are needed prior to applying power to the circuit, double check connections, then apply power and read your measurements. Then turn off the power, remove/reposition the probes, and continue.
I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.

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