That would be on another WD2500JB Caviar harddrive
Either that, or start looking on the internet posting -
WD2500JB PCB Board, and see what search hits come up.
Here,.....let me try.............http://www.hdd-parts.com/18100096.html
Before you replace it, let me ask........
1) Was it in a Desktop PC?
2) Was it in an external harddrive?
Then suggest you obtain a 3.5 IDE (PATA) external enclosure,http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=3883498&CatId=2780
In an external harddrive there is a small interface circuit board.
The Harddrive plugs into the small interface circuit board, and the USB cable is attached to the small interface circuit board.
It is this small interface circuit board that usually goes bad.
The external enclosure is just like the case of the external harddrive.
Has a USB cable going to a small interface circuit board, and the harddrive plugs into it.