There are some good ideas here. Here's my take:
In #1, the top part is interesting, but the bottom doesn't see to complement the top part. I'd just chop it off, unless there were some way to change it. In #3, the yellow frame looks like a cage, kind of a protective cage around instruments to keep things like people and forklifts from bumping the instruments. This is good, since I can relate some sort of function to it. In #2, though, the yellow bars didn't give me that impression, and seemed to be a distraction from the interesting goodies in the background. If all I were looking at were #2, I'd prefer the yellow be a more muted color.