Hello friends.
It's sometimes essential to know someone elses experience. I thought such post may be helpful for everyone in the future, so here goes the case:

Is it ALLWAYS neccessary to match both 2 lines of PCB sticker to have success in PCB swapping? (with NVRAM resoldering ofcourse)

I matched anything but the last digit in second line of this PCB sticker
The drive is HTS541040G9AT00 ATA 2,5" Hitachi 40GB Travelstar (year 2006)
MLC=match
P/N=match
model=match
S/N (without 4 last digits)=match
PCB rev=match

only this little thingy on the end of second line makes me worry..
Patient PCB not repairable. I'm just curious IF in this case, I may be lucky without this second line match?

You should be OK.

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Tried, and it didn't work.. drive seems be perfectly normal, spinning without any strange sounds, nvram reading OK, goes ready BUT no possibility to read data nor read any fw module. I uploaded the nvram reading from patient PCB to the donor, without soldering.
Head map is identical.. But i see now a difference - MADE IN PHILLIPINES. The patient PCB is made in China.. so I gave up, didn't work for me. Uploaded the original nvram again and the donor drive works perfectly :/
Looking for another donor, will try a closer match this time

Hmmm... are you sure you did everything right? Hitachi going rdy but no ID and abrt err sometimes means rom incompatible.

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Are you doing this for research, or are you working on a failed disk? If working on a failed disk problem can be elsewhere, maybe SA has some errors.

With new PCB and patient NVRAM can you reach SA and read it?

It's a work to be done, sooner or later. Only thing that comes to my mind, is that maybe original nvram went corrupted. But IF this is the couse, I still need to be sure if the donor is compatible, and maybe then try to regenerate using SalvationData option for nvram (but it takes hours, days, weeks)
I'm sure I have patient original NVRAM, saved on my computer (I have read it to file after resoldering chip to previously tried donor)
No access to SA modules at all, hddguy.
Donors are OK. I would suspect the drive, if I only had a closely matched donor. But the donors were not so closely matched, so i still think it's not the drive's faultt. Couse the patient drive was working OK, till one day It stopped spinning. PCB was dead, although no visible damage (are there anywhere even any TVS diodes on those old laptop Hitachi's? nothing is burned with fire, just doesn''t spin up the motor when attached to whatever drive)
If ROM can be incompatible, as You mentioned northwind, may it go "ready" without access to firmware nor user area? Closer matched PCB can fix this issue, am I correct?

The 5K100 has a fuse, so presumably the TVS diode, if it exists, will be adjacent to it. Show me the other side and I'll point it out to you.

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A backup a day keeps DR away.

Yes I have seen this happen.

_________________
http://www.northwind.gr
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Ransomware Reverse Engineering - NoMoreRansom! partners

Yes.

Thanks for answers. I attach some close-up photos.

Obviously there's a fuse (F1) plus a zero-ohm resistor.

There is also a 3V test point. This should tell you whether power is getting to the board.

I can't recognise any TVS diode. There is a D8 near the motor controller, but I can't see how it connects.

_________________
A backup a day keeps DR away.