fried arduino

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

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

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).

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

DavidFoe: 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.

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.

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?

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?

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

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

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.