Possibly, static electricity damged the PCB i.e. you weren't ground properly when you handled the PCB or the bad drive had a dead short which damaged the new PCB.

>I put the PCB of my good Quantum hard disk on a bad
>hard disk in order to try to recover data
>
>Unscessfully, I put the PCB back in my good HD but
>it does not work any more
>
>I can not imagine what may have happend
>
>Is there any software able to detect my hard disk even
>when my PC setup does not detect it anymore ?
>
>The HD is and IDE type, not Sata
>
>Moises