I have a Seagate Momentus 5400.3 160GB:

  • Model: ST9160821AS
  • PN: 9S1134-042
  • FW: 3.CAE

I want to replace the PCB on the drive but I can't find any PCB's or drives with the exact PN and FW numbers. Do these matter or is the only requirement the model number? I don't mind buying the same drive and removing the PCB either, I'm doing this more to play around so I don't really care if it works or not but I want to make sure I'm doing it right.

2 Answers 2


I haven't done this in several years, but it used to just be finding the same model # and swapping the PCBs. It was a great trick for recovering data for users when doing hardware support. I imagine you could run into issues if the FW/PN change modified motor manipulation with respect to the platters or using different internals, but I bet that is the edge case.


Drive's firmware contain tables that are written there during the manufacturing, with calibration data and other pointers that relate to the exact those platters that are in this specific hard disk.

Replacing PCB with a different one, even same model, would either not work at all, or not work reliably. You need to copy that data from old PCB to the new one. If the PCB on the old drive is completely dead, and this data is important to you (read: worth more than several thousand dollars), I think you should turn to professional data recovery services.

From http://www.harddrive-repair.com/pcb-repair.html:

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

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