I went to Lincoln for the EAA board meeting. Afterwards, we went to the hangar to see the sign all lit up, only it... wasn't.
As there are 3 strings of LEDs, I figured it had to be a power problem, and we checked the wiring and everything looked OK inside. The problem was the (old) 12V power supply we'd thrown in - it was putting out ~3V. Jim had a 9V power supply in his car, so we tried that and everything lit up. Ron was suitably impressed :o)