Hi.
due to improperly connected power cable pcb burned 
repairing possible?
Max.
Yes i think can be possible, but you have to find out what was damaged, can be not worhty if you don’t mind about data … if you need data is better to contact a data recovery company as in these drives you can’t simply swap the PCB due to adaptive data in ROM.
Bye
Luca
Often the problem is only a shorted diode, in which case there is usually a zero-cost DIY solution.
See http://www.users.on.net/~fzabkar/HDD/TVS_diode_FAQ.html
Upload a detailed photo of the component side of the board if you need help.
Here is an example of the affected components:
http://www.users.on.net/~fzabkar/HDD/bigcircuitboard_diodes.jpg
