With light amounts of water on your equipment and circuitry, it doesn't harm much unless you turn it on while it's wet, and the water becomes conducive and shorts shit out. But if you cleaned it carefully, then used a fan for a while, then turned your equipment on the next day, it would be fine. It just depends on how much water we're talking about.
My advice would be to take the thing apart. To clean just the keys and the chassis of the keyboard, you really wouldn't run much risk in fuckin up your keyboard.
But do it
carefully...
Every screw you take out, have a piece of paper down with a small diagram (just a little box) of your keyboard. Lay the screws on specific parts of the diagram so you remember where they were. You may have to buy a hex bit or torx, depending on what model it is. There may even be information on how to take apart your keyboard online, if it's complicated. I took apart my entire G4 Laptop, and it was a pain in the ass, just to install a DVD burner. But I found the info online, and studied the diagrams, then did the procedure backwards. There were more than 40 screws, but it worked fine. And if I could do it, then you can do it too.
Some keyboards are really hard to get to, like the Korg Triton. Here's an example of someone who has replaced keys on his Triton:
http://209.35.182.75/trinityhaven/HTML/tritonTUTbrokenkey.htm
Found this on another forum:
This may help.
Place your motif on the cushions of your couch or on your bed, then remove the end sections like you did before. Flip the motif over, and remove the many screws on the bottom. Carefully flip the motif back over, holding the control panel in place, so it won't flip open as you turn motif over. The panel is hinged in the back, and will easily open when you lift it up from the front. This will give you a better perspective and will expose the keys for inspecting. I replaced the control panel on my motif 8 last year.
If you're not comfortable doing this, by all means take it to your nearest Yamaha dealer. They will probably only charge you about $150. You must remove all the screws from the bottom, except for the keybed lip rail along the front. You do not have to remove the end panels. There's one you can leave in the bottom, but it isn't obvious, so just take them all out... A powered screwdriver or VSR drill w/phillips bit helps. Good luck.
I didn't really look that hard... I'm sure you can find more material on the subject. Not to mention I don't know what kinda keyboard you have.
