I might have missed something, but here's what I perceive as a problem: I bought two new cables from SparkFun to provide power by X1 (the barrel connector)
AC Adapter- USB to 5.5mm Barrel Jack adapter
For some reason my LCD didn't light up... testing power, I found that I was only getting 3.3V at the 5V pins.
I assumed that the barrel would be able to supply 5v, and I see at the ends of the cables that it's putting out 5v, but by the time it gets into my Duemillinova, it's stepped down.
If your wall wart is providing exactly 5 volts, then that is the problem. Due to the way the arduino regulates the power supply, if you provide it with less than about 7 volts, it will not be able to provide 5 volts to the board. I would recommend using a wall wart which puts out between 9-12 volts. at 12 volts or more, the voltage regulator will start to generate more heat that can easily be dissipated.
Ah... it's the old 5V-needs-to-be-greater-than 5V problem! My goof. The 9V wall wart is out of stock and I went with 5V thinking it would give me 5V on my 5Vpin... my bad. Same with USB:
What's the purpose of the USB to barrel cable adapter? A wall wart DC power module with the proper barrel connector would plug into the Arduino's external DC power connector not it's USB connector?
Got ya. Be careful using that USB to barrel cable as if you were to draw too much current, without some form over current limiting, from your PC's USB connection it can be damaged.