You know that capacitor on the back of the display's PCB? The one that David points out in the how-to-remove-the-drive-tray video? What does it do? Or, rather, what would it break if it were broken?

The reason I ask is that I was swapping some drives earlier, and I noticed that mine had a bad solder joint on the upper leg. Enough that I could have actually removed it from the PCB had I tried hard (which I didn't). I tacked it back on with a dab more solder and it seems solid now (and the empeg still seems to work -- fortunate, given my clumsy hands).

However, I hadn't noticed any problems before. Is it possible that it was making contact enough that it was working within spec? Or am I just too blind to notice an obvious problem?

Isn't it something to do with generating the HT for the display?