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[on:]

So I was not paying adequate attention (or wasn't thinking) and I shorted the 5 V pin to ground.  I only noticed it when the smoke appeared!   Now the 5 and 3.3 V pins are not regulated (they drift between 3 and 7 volts).  Is there a fix or is it scrap? 

David

[Reply #1 on:]

Depends - where are you located, and what kind of board?
Some parts are more readily replaceable than others.

[Reply #2 on:]

Located in New England (RI) and it is a Uno (not the latest one, it runs ver 022 but less than a year old and not surface mount).

[Reply #3 on:]

Sounds like you need to remove/replace the 5V regulator, and possibly the 3V regulator, depending on which Rev you have - look here and see which one it is.
http://arduino.cc/en/Main/ArduinoBoardUno

[Reply #4 on:]

Located in New England (RI) and it is a Uno (not the latest one, it runs ver 022 but less than a year old and not surface mount).

I'm sure someone will correct me if I'm wrong, but v. 022 is referring to the software. (Not sure exactly if that encompasses IDE + libraries + bootloader, or how that's arranged.) There is an R2 and and R3 Uno board. But I think you can use v. 022 or v.1 with any of those, or the original Uno. For that matter, you can put a custom bootloader in, and still use either IDE.

[Reply #5 on:]

Correct.

"For that matter, you can put a custom bootloader in, and still use either IDE. "
Maybe - bootloader also determines the speed the serial port needs to be for downloading a sketch.

[Reply #6 on:]

It's a uno rev.2 with the reset button in the middle of the board (rather than the corner like rev3).  And, you are right, I meant to say that It runs software IDE version 022. 

How does one identify the failed 5 V and 3.3 V regulator components and find the correct replacement parts?  Is there a map/spec or something?

[Reply #7 on:]

If it's a Uno rev 2 then if you hold the board with the barrel jack at the bottom left, the 5v regulator is the device right above the barrel jack with 3 leads on the right and a tab soldered to a heatsink pad on the left. Is that where the smoke came from?

[Reply #8 on:]

Where was the 5V being supplied from when you shorted it?

[Reply #9 on:]

Yes, the smoke (really just a lot of heat) came from (or near to) the component that you describe: 
"device right above the barrel jack with 3 leads on the right and a tab soldered to a heatsink pad on the left"

The 5 V was being taken from the 5 V pin (which sits next to are near the 3 volt pin) and until I mucked it up (and caused a short) was supplying voltage to a potentiometer which was being read by A0 (on the same side of the board as the 5 V.  AO was still attached to the pot when the incident occured (duh, lets swap the +5 and GND) so that part might be ok.

I suppose I need to look and see if I can see a part number on the regulator

[Reply #10 on:]

I'm surprised the device failed, regulators are usually short circuit proof.

You can find Arduino schematics and parts lists in the Hardware section of the Arduino main site.

PS - looks like it is NCP1117ST50T3G.