I was fixing my wifes laptop (an ASUS R1F) because it wasnt charging. Turns out the problem was broken connections on the input plug, but while investigating I noticed the first device that the power connected to was an 8C12. It looks like a 3 terminal voltage regulator and I assumed it would be 12V out. However when looking up datasheets for the 7812 devices and comparing the pinouts of the SMD versions, on mine the pins are reversed. ie when looking at it from the pins side, the input is on the right.
The other surprise was that when I got the plug resoldered I measured the output of the device to be 5v when the 19v powerpack was plugged in.

I cant find 8C12 as a device using google. Does anyone know what for sure what it is. Its an SMD so doesnt have any other markings.

 

It could be a 5 volt regulator, or a zener, or a npn transistor. It depends on what package it is. The following link is a catalog of SMD codes.
http://www.dl7avf.info/charts/smdcode/index.html

If it is a SOT-89 package, there is a good chance that it is the following device...
http://www.datasheetcatalog.org/datasheets2/21/213989_1.pdf

 

I think it is probably the SOT89 package though the letters were not in corners as shown, they were just in a line as '8C12'. Your reference proves that packages with that lettering could be a 5V regulator, so I guess thats what it is then.
There were no other components to suggest that it was a transistor of any sort, ie no biassing resistors etc. The input from the power jack was connected to one pin, common ground to the middle pin, and the traces on the other pin went off into the cct board.