My RME Fireface 800 audio interface died! One day it's fine, the next... no lights... no sound... nuthin... Fortunately, this problem is fairly well documented on ye ol internetz. (This video on the topic is pretty great.) Apparently the electrolytic capacitors in the power supply dry out over time (as they do in most electronics).
One option is to find the offending cap and replace it, but since it's not too expensive, I went for a full recap of ALL the electrolytics on the power supply. I found a useful forum post that detailed the specifications of the caps needed to do a full recap. They recommended using low ESR caps. I had a really hard time finding low ESR caps, but I'm 100% positive all the caps I used are better than the no-name stock ones that the manufacturer put in it. Here's a list of the caps (and quantities of each) I used in case you're doing this repair too! You can also click this link to find all the same parts at digi-key.com (if they still have them): http://www.digikey.com/short/p9r2zb
Once all the new caps were in power was restored and peace and justice returned to the universe! Who knows, with better capacitors than it's power supply had when it was new, maybe it will even sound a smidge better too. Below you can see it happily reunited with it's tribe of misfit gear; the Furman that I put a new front power socket in, the Symetrix 528E who's input I repaired, and the PC cobbled together from parts, and even the power cable that nobody wanted because of a scratch in the middle of it that I turned into two good power cables.
If you're a student at a music or film production school and they make you take an electronics maintenance class, pay attention! You can do some neat stuff with that information and it's not quite as hard as it looks at first.