I accidentally touched the 12 V prong of the connector to the 5 V side of the HDD and the drive is now dead. Would a PCB replacement fix this? Or would this have fried other components, too? Here are the specs:

WD800BB-53CAA1 80 GB

Board: #2060-001092-007
Main Controller IC: #WD70C23-GP
HDD Motor Combo IC: #L6278 1.2E

Dogman11

Check the TVS diodes most likely just blew one of them if your lucky. Google the term TVS Diode or search here many many posts about it with plenty of info no need to repeat it here Good luck with your recovery

I have a similar PCB. Mine doesn't have any TVS diodes.

I expect that your board has probably sustained major damage.

_________________
A backup a day keeps DR away.

Yeah I don't think mine has TVS diodes either (note the missing diode at D3 in the picture below). The board is a 2060-001092-007 with the following specs:

Board: #2060-001092-007
Main Controller IC: #WD70C23-GP
HDD Motor Combo IC: #L6278 1.2E

Do you think it's worth trying a PCB replacement? If so, does the HDD Motor Combo # have to match? Which chip would need to be transferred from the old board to the new one?

Here's a picture:

I don't know what is required for a match, but FWIW the OP in the following thread had success with a straight board swap:
wd200bb-00caa0-fried-but-not-completely-help-t21978.html

I can't say whether his conclusions were correct, though. I would have thought that the DCM only mattered when swapping mechanical parts.

_________________
A backup a day keeps DR away.

I've seen some posts that say a chip transfer is required after a new PCB is installed. It's referred to as the ROM, U12, or EEPROM. How do you know which chip to transfer?

I'm not a data recovery professional, so I can't advise as to whether a chip swap is required on that particular board. In fact, I see too many posts where the pros themselves can't agree on such things.

What I can say is that the EEPROM is a parallel type rather than serial. It is located in the bottom right corner (U2). Current models have "adaptive" information that needs to be transferred (U12), but on older boards you may only need to match the firmware (or not?).

_________________
A backup a day keeps DR away.

My WD800BB doesn't have any reference to firmware code like a Seagate does.

Here's what's on the drive:

Drive Parameters: LBA 156301488
MDL: WD800BB-53CAA1
Date: 20 MAR 2003
DCM: HSEHNA2CH

Then there's 2 other unidentified numbers above UPC barcodes:

WMA8E6217408
5502352