The PCB on my Hitachi DeskStar hard drive went into smokes after connecting it to a newly purchased SATA to USB adapter. So I replaced my fried PCB with an identical board and now the drive spins but is not recognized by the BIOS. After doing a little research I found out that I was suppose to solder a chip (NVRAM/Rom) off of my fried PCB and onto my new PCB. But I am confused about which chip this is.

Here is the image of the bad PCB:


The section that I have labeled as A reads;
S93C76
ADVH4
8476

And the section that I have labeled as B has no visible chip.

Here is the image of the good PCB:


The section that I have labeled as A reads;
S93C76
ADVH3
7312

The section that I have labeled as B reads;
Pm25L V010
AE0807
M05265L

And here is a comparison image of the two;


Why does my bad PCB not have a second chip like the good PCB? Also, do I solder Chip A off of the bad PCB and onto the good PCB? Any help would be GREATLY appreciated. I had a company quote me on how much it would cost for them to recover the data and its way out of my budget.

Yep, switch A and you should be okay. The contents of B exist inside the MCU on your original board.

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You don't have to backup all of your files, just the ones you want to keep.

I am a little bit confused - didnt learn yet, that one should desolder / solder 2 chips.

Might be specific for this board - but do they really match?
What is the content of A ? what type of chip?

Isnt only B the nvram, where the rom is stored usually (in case of the designated donor pcb)?

But, how does that work, when the "defect original" is a newer pcb without an external nvram,
because rom is inside the mcu?

+++

Without having it in front of me, I would say that A is the NVRAM and B is the ROM, which is sometimes in the MCU.

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You don't have to backup all of your files, just the ones you want to keep.

Hi

First of all, backup all the memories before any try!!!
The missing one is an external rom, wich can be different form the other board, so it can corrupt your NV-RAM as well!

Janos

How do I perform a backup on the NVRAM?

with pc3000 or external programmer.
But you MUST to backup the ROM too, because i have seen a lot of times, this can be currupted too...

Buy an external programmer.... for the working drive you need something like PC3000 or similar...

Thank you for all the advice you have given me. Any idea of how much a unit like that costs?
Thanks again

Pc3000 Udma = about 10'000$, external programmer, from 'toys' about 200$ to 2000 $/€ like the one I use. Yes, all 'zeroes' are right.

This really is not a good job to DIY. You are going to lose your data

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Zero Alpha > https://zeroalpha.com.au