arduino + unsped shield won't power up!!

Hello,

I just finished wiring the unsped shield,and the moment I connect it on arduinome, arduino powers off.
I tried again with external power supply and the same thing keeps on happening.
Finally I tried without the leds connected to the shield and again tha same thing.
I also disconected every pin from the shield and only left tha four pins related to 5V power , Ground and Vin and these are the pins that cause the arduino to power off (although I dont know if this is helpful at all as info :-p)

any ideas?

This is the shield? http://unsped.blogspot.com/2008/12/arduinome-shield.html

It looks like a pretty simple and straight forward design. So, the first thing is to check your soldering, look for shorted traces (get a good 15x magnifying glass), reversed polarized electrolytic cap, one of the IC chips installed backwards. Sounds like something is pulling enough power to pop the polyfuse.

Yes this is the shield!

I should mention that when I tried to attach the shield the arduino was already connected to my MBP and I got this error message : Beacuse a USB device was drawing to much power from your computer,one or more of your USB devices have been disabled. After I got that message I tried external power supply and the same message appeared.

I am checking the shield but it looks ok (I dont have a magnifying though)

Is there a way to find out in which way I should attach the chips (if there are directional)

Is there a way to find out in which way I should attach the chips (if there are directional)

Ouch! The chips are directional (if that's the term you want to use). DIP (Dual Inline Package) chips have a pin one that needs to go into the board pin one. There will be a dot over that pin and sometimes the component mask is marked with a 1 near or a square around the hole. They also have a notch in the top to signify the end that has pin one. Aline that notch to the one shown in the component mask (the U indent on one end) on the board. If you have installed them backwards, they will be fried and you'll need new ones.

Did you buy this as a kit, or did you make the circuit board yourself?

sorry for my english but is's not my native language :)

I have a spare shield, which btw I ordered through a group buy @ monome forum, and noticed that the same problem is happening with only the capacitors attached to the shield.

I use 3x http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=P4910-ND which was suggested by the creators of arduinome here http://flipmu.com/work/arduinome/hardware/

Is there any chance the capacitors to draw big amount of energy to make everything shut down?

Can you post some up-close pictures of the board (both sides) that has only the capacitors installed?

The electrolytic capacitor (large one next to the A0 thru A5 pins) C2 has a negative and a positive lead. The positive lead should be soldered to the square pad, the negative lead should go to the round pad with the minus (-) next to it. If this is reversed, it will effectively short +5V to your ground rail.

The rest are standard ceramic bypass caps and have no polarity.

With capacitors being the only items installed on the board, there should be no current flow. Capacitors don't pass DC current.

Actually I tried with jumper cable instead of capacitors,which I dont know if it makes any sense (newbie) and the same thing happened. So I leaped to conclusion that my soldering was problematic.

check the photos though http://www.flickr.com/photos/feltcollective/sets/72157623054748661/

and again thanks :)

In the photo DSC03071, the leftmost IC is inserted wrongly (must be reversed). This may be the case for the middle IC as well (can't tell for sure from the photo). You need to match the notches on the ICs with those on the silkscreen.

I don't see any obvious solder bridges (solder blobbed from one pad to another -> short).

The electrolytic cap has the printed negative band going to the proper trace.

All the IC's are in backwards, the notch on each should go to the side of the board that has the electrolytic capacitor. I'm working off the original Eagle board file and don't have a way of posting the exported image so you can see this. On assembly, there should be a notch in the IC socket that matches to the notch on the silkscreened IC chip outline. In future, keep an eye out for this and make sure it matches. Then when installing the IC chip, match the dimpled notch to the notched end.

RN 1 is a resistor network. It has a pin one, usually indicated by a dot. Make sure that the dot is matched up to the 1 on the silkscreen.

All the other components are non-polarized and therefore should be fine.

Ok,

I soldered my spare unsped shield
and turns out that I did some horrible soldering at the previous one,for this one workds fine!

Now another problem occured which I am going to transfer to a new thread.

While arduinome is recognised by arduinomeserial on windows,
on mac it is not!