The Printed Circuit Board controls many functions to operate the hard disk drive, There are 5 main features of a the electronics that can be unique to each drive that is likely to fail, the first being:

 POWER INPUT
 The most problems we see here are mostly human era... forcing the power plug in the wrong way
Unfortunately apart from a few notebook PCB's the is no protection fuse to prevent PCB Damage
There is also risk of power surges making it through to the electronics as well

FIRMWARE
Firmware is unique to the PCB this controls calibration and track information so it is very rare to be able to interchange the same model PCB with one that has another firmware revision... so what this means, if your board shorts out the firmware unique to the drive, you will be in trouble. Of course a good main stream data recovery company will be able to replace this and manually reprogram this chip

SPINDLE IC
This controls the speed and rotation of the spindle rotating the platters internal to the hard drive assembly or HAD
These intend to get very hot at times and can often short out… The most famous of models to this was the good old quantum LCT, particularly the TDA5247HT Chip; this would go up in smoke and leave a pin hole or a very big mess on or over the IC


MICRO CONTROLLER
These rarely fail unless there has been an extreme hit by power such as a lightning strike that may cause voltage through the IDE Cable. If this does fail you would normally find visible damage

TRACKS
Internal track are the thin Copper ribbons that run through the board that connect each component these can be easily damaged bay any of the above case scenarios, but one of the most common that I have seen is Corrosion
Below is a great Example of how quickly chemicals in the air from industrial workshops or even sulfa in the air from volcanic regions can cause havoc... but for most residential computer hard drives its condensation that damages a PCB

In this example this PCB was only 6 months old


WARNING IF YOU CHANGE  A PRINTED CIRCUIT BOARD WITH A NON MATCHING PCB... SUCH AS DIFFERENT FIRMWARE, LAYOUT, OR MICRO CONTROLLER NUMBERS, YOU WILL RUN A HIGH RISK OF FAILURE AND FURTHER DAMAGE!

Yes there's a high chance...

 YOU WILL SEE SMOKE!!!!!!

 If you have an exact match to the PCB you want to attempt swapping, the risk will be minimal but what allot of people don’t realize, is that code can change overtime even with exact matching parts.

What this means is... if you were to purchase two NEW exact hard drives at the same time from the same batch and then swapped there PCB's to each other, you would most likely be successful!

Try that same scenario 6 months after heavy use... and results will could be very different
There's a high chance that each PCB has made themselves unique to each drive!

How can this be?
Its called SMART Technology where the hard drive is designed to reconfigure itself during operation to maximizing performance and protecting data.  If a sector is read slow but functional the drive will remap this sector as bad and move this sector creating changes to track and sector information in firmware
Now this new reconfigured information is unique to the drive, and can cause this PCB to be incompatible with any other drive of matching numbers.

As a data recovery engineer it is always best to repair the Original electronics of a failed hard disk drive
That way you get maximum results with very little risk, Most high end data recovery companies have the expertise to replace many, if not all components on the PCB.. but not only physically but replacement, but this may also involve new components and reprogramming.