Head transplant questions (ST1000DM003 1To)

[Bloushoops]

Hi guys,

First of all, I'm a total novice of this fine art which is hard drives troubleshooting and repairs, pardon me in advance if I'm mislead on what I'm about to write. I'm willing to learn through failures and retries, and this is why I'm posting there, hoping to find educated explanations about what I'm about to execute. Quick disclaimer, I've an average knowledge about electronics, as I'm a hobbyist since 10y+.

I have 2 compatible Seagate ST1000DM003 1To HDDs (I believe those are F3), I confirmed it with charts from donordrives. Every values that has to be a mandatory/recommended match is OK. They were both bought at the same time, which is probably why they are almost identical. I'm using those drives since many years, and one of them has shown signs of what I believe is a critical hardware failure.

The first disk, disk A, is fine according to S.M.A.R.T readings, and is on the process to be decommissioned from a secondary NAS I have at home. I can access its content without any trouble. The second one, disk B, is a backup of the first, and has failed beyond software recovery possibilities.

Symptoms of disk B failure ;

• power-on, on a 12V PSU/SATA power cord,
• disk starts spinning,
• 2 distincts clicks (I think the heads are looking for something on platters, then go back to park),
• disk stops spinning (I think it's unable to initialize, or read something, then switch to a security mode where it mechanically powers off, until a new power cycle is done),
• absolutely no suspect sound, I guess the platters are ok, and heads are not scratching anything (both disks never encountered physical events, like being dropped, nor any sort of temp change, nor chocs),
• no burn smell, no distinct electrical failure of any sort,

I then tried to troubleshoot with this procedure ;

• checking PSU on SATA, voltage readings are OK,
• visual inspection of the PCB, no sign of failed components,
• thermal inspection of the PCB while powered-on, looking for hot-spots with a FLIR camera, everything seems in acceptable temp ranges,
• electrical testing of diodes, and 0Ω resistors, on PCB, everything is OK,
• reading of "BIOS" firmwares with a CH341A clip/USB, both chips are readable and contains the respective disks informations (S/N, and other informations),
• S.M.A.R.T reading are fine for disk A, but totally innaccessible for disk B, the only info is the infamous 3.86GB capacity reading,

With those informations, I think I've managed to successfully pinpoint the failure, after having thoroughly read the common problems that those disks encounters, both on this forum and Google. My bet is a SA reading failure, which strongly implies to do a head transplant, as being the best course of action for this kind of critical failure. The common other usual solution for problems on this disk is a PCB transplant, and swapping the "BIOS" content from donor to patient, containing infos about physical reading offsets and defectuous sectors, but it appears that this solution is 9 out 10 times not the correct one for this case.

Thus leading me to my question (sorry about the lengthy intro) :

I'd like to try a head transplant, taking heads from disk A, installing them on disk B.

As I've previously said, recovering data on those disks does not matter, I've online/offline backups, so their soon to be next resting place will be a bottom drawer in an obscure workbench where my electonical components can find a dusty peace after a long distinguished service. I fully understand that having not the right tools, nor the experience, and working in a non-sterile environment, will probably destroy both disks beyond any possibility of recovering. That's fine for me. I just want to try to do it myself, driven by curiosity.

What I understood, from the datasheet of those drives, is that thoses disks only have 1 platter, with 2 heads (one on each platter side).
I've a set of basic tools, screwdrivers with torx heads, antistatic gloves, plastic "separators" (I'm not sure what the correct name is).

What I'm missing, and I'm not sure if in this case I need it, is a head comb.

If I'm correct, the purpose of a comb is to prevent heads from touching, or bending them during manipulation.
And this is what I don't understand.

Why having the need of a comb, if heads can naturally go to a park position, thus already having the correct spacing between them, and why is it needed if the drive only have 1 platter ? Is it only for security purpose during manipulation of heads ?

If I need them to maximize the success of my experiment, is this kind of "comb" adapted for this kind of drive ?



Disks infos ;

SN : *4Y*****
Modèle : ST1000DM003
FW : CC45
PCB : 100724095 REV A

Thanks for any valuable insight you will be able to give,

[northwind]

Because when the heads are removed from the 'park' position, if there's no comb to hold them in place, they will touch each other and stick (game over).
1 platter=2 heads, so these heads need to be separated.
Additionally, a comb will help maintain balance and tension on the heads. Mind you, they're very fragile.
You're going to have to find a comb that is a perfect fit for your model. Not all 1-platter combs will fit.

As I've seen you've done quite a homework, so instead of going through all the DIY warnings, I'll just note that even if your head swap procedure is successful (which I doubt - no offense), you're going to need a tool to have the drive imaged. It's not a 'swap-heads-connect-and-copy-data' procedure.
Good luck!

[lcoughey]

I suggest you start by removing the heads from the good drive and putting them back in. If you do it and the drive still works, you can then try the swap to the bad drive.

[Bloushoops]

Hi,
Thanks for your advices, I better understand why it's mandatory.
I'll try to do it on the good drive with some heavy files, and see if it has become corrupted
I'll keep you updated,
Cheers,