This is not true, a PCB swap will NOT work on most modern drives, you MUST transfer the firmware chip as it contains drive specific data. If you're not comfortable doing this soldering work, I'd bring it to a locak electronics repair show and have them move the chip for you.
I have the new pcb and as u have said, bios chip needs to be swapped. How do I swap the chip? What tools and technics are needed to take the chip off the pcb? What tools and techics are needed to intall chip onto pcb?
but... tell me the difference... I have replaced the whole pcb... What exactly does the bios on the hard drive pcb do? But the pcb seller also told me to swap out the bios chip before I bought it. My plan is to recover the data lost, and make this HD an external storage. Am I on the right track?
The PCB usually has an 8-pin serial flash memory chip. This chip stores "adaptive" information that enables the microcontroller to locate the firmware modules in the hidden System Area on the platters. Modern drives also fine tune the heads to account for their spread of characteristics (eg differences in frequency response). These calibration constants are determined at the factory.