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 Post subject: Head stack doesn't move
PostPosted: March 7th, 2023, 23:59 
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Joined: December 1st, 2014, 0:07
Posts: 8
Location: America
I need some help from an expert who might give me some suggestions with a drive recovery issue. This is about a Seagate 4TB ST33000651NS drive that suddenly stopped working a few weeks ago. At first, it could be seen in Disk Management, showing as "Unallocated", with no sign of the partition or files that were on it. That led to everything below.

The background info:
After a bit of testing on my own, I took it to a good data recovery company who looked at it and reported that "test results for your failed hard drive are in and have shown that the Head Rack Assembly is the failure mechanism". I'm not exactly sure what they did to determine that, but it's a very well regarded company and so I presume they knew what they were talking about. Unfortunately, the ~$2K cost was out of my ballpark for now, maybe forever, so I've had to learn everything I could and try to fix this myself if I hope to recover anything from it.

I bought the right tools and the right head 'comb' gizmo to slide between the heads to safely remove them without damaging them or platter, etc. I bought a couple of donor drives that matched all the exact criteria, built myself a small clean room area, mask, gloves, etc., and watched plenty of videos to be sure I knew how to change the head assembly correctly. I say that only to point out that I've tried to be very careful and do it right. After all that, I managed to replace the head assembly without any apparent problems (that top magnet is freaking strong and was probably the toughest part to get off and on carefully). The head assembly appears to be exactly where it should be, it does not appear to have any damage (seen under magnification), and I can gently swivel it a bit toward the platters, so I know it's not binding. I also bought a matching replacement PCB and a complete hot air soldering kit to remove my bios chip and put it onto the replacement PCB, which I did. That went perfectly, as far as I can tell .

So, the problem now is:
Connecting the drive now, it doesn't even show up in Disk Management. The disk spins up for about 20 seconds, then spins back down (with no clicks or other odd noises). however, I've managed to test it to see if the head assembly moves, but it never moves at all...not so much as a twitch. As mentioned above, the heads do rest nicely on the small yellowish plastic parking fitting and they can swing smoothly toward the platters with no restriction, based on my checks. But when the drive is connected and powered on, the platters spin up but the head part never moves out of the parking spot toward the platters. Twenty seconds later the heads spin down and nothing more happens.

As an aside, I have noted that if I try rotating the platters manually counter-clockwise and sliding the head assembly gently over them, I can barely get the heads over before they seem to lock onto the platter, and everything feels stuck in place. I don't know if that's normal or if something else needs adjusting, or if that wouldn't happen if the platters were already spinning 7200rpm. I just mention it in case it indicates anything.

So, at this point I'm stumped. I'd appreciate any suggestions from anyone with any expertise. I can swap in another head stack assembly or try another PCB board if there's reason to think the ones I've already swapped out may still be bad. But any help at all will be appreciated.
-JT


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 Post subject: Re: Head stack doesn't move
PostPosted: March 8th, 2023, 3:20 
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Joined: March 11th, 2019, 6:41
Posts: 13
Location: Romania
Does your HDD have TTL pins? Near SATA connectors there should be 2 / 3 /4 pins where you can connect a TTL adapter and inspect the errors/messages coming from the HDD.

If you want to test you head assembly swap skill you should try it on a working drive, pull the HSA out, then put it back in and test.

I like your dedication! You probably won't fix this HDD but you will definitely learn a lot!


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 Post subject: Re: Head stack doesn't move
PostPosted: March 8th, 2023, 6:13 
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Joined: January 28th, 2009, 10:54
Posts: 3452
Location: Greece
This is a 3TB drive, not a 4TB.

Before you send it to the DR lab, if the drive wasn't clicking and spinning down, but just not showing up in Disk Management as unallocated, then most probably the heads weren't the culprit in the first place. These drives are famous for all sorts of different failures that aren't heads-related.
But now that's a different story.

There are a few things you need to check: a) is the PCB still native? You can determine that by reading the ROM and comparing the reported s/n and the one on the label. b) Did you follow some matching criteria for the heads assembly? You need to match certain things to have compatibility.

JTT wrote:
I can barely get the heads over before they seem to lock onto the platter, and everything feels stuck in place. I don't know if that's normal or if something else needs adjusting, or if that wouldn't happen if the platters were already spinning 7200rpm. I just mention it in case it indicates anything.


This is not a good idea. The heads shouldn't touch the platters at any point. When the drive is in operation and rotates at 7200rpm, a tiny 'bed' of air is being formed between the heads and the platters that makes the heads 'fly' over the platters and not touch them. That is the reason why the drive should never, under any circumstance, be operated with the lid open. The reason is, when you run it with the lid open, the internal pressure is not enough to maintain that fly height and the heads crush onto the platters.
Additionally, if you moved heads onto the platters, felt them being stuck there and then moved them back onto the ramp, most likely the heads are now damaged too.

I agree with the advice given, connect terminal and let us know why the drive complains, but most likely it is damaged heads and media now.

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 Post subject: Re: Head stack doesn't move
PostPosted: March 8th, 2023, 22:17 
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Joined: December 1st, 2014, 0:07
Posts: 8
Location: America
Thanks for helpful replies, and even the dismissive one. For now I'm still willing to attempt what I can since I know I'm cautious and reasonably competent. Even so, I'll only go as far as I feel I'm not damaging anything beyond what may already be the problem.

To answer Ghimpe, this Seagate drive does have the four TTL pins, so I'll get a TTL-USB adapter to connect to them. I found some information online that should help me get the errors or messages you mentioned. I'll get back on that asap.

Replying to Northwind: I've been as careful as I can to verify the exact models/numbers of both the drive itself and the PCB, since I've noted how important all of that is. I made sure, as much as possible, that everything printed on the front of the drive that needed to match (model #, Site, FW, first part of the SN#, etc.) did match my donor. I also checked with a couple of PCB donor sellers to ask what must match for a donor PCB. From what they told me, I think the donor PCB is also correct (though I'm trusting what I was told obviously) and that all I needed to do was swap the BIOS chip. That said, I realize I'm limited by not having high-level equipment (like PC-3000) to use to check for problems. I do have a number of the most recommended software applications for data recovery that I might try, but only if I ever get to where I can read the drive again.

I agree and I know that it's a bad idea to move the heads across the platters. Actually, I did not run it with the lid off, I found a creative way to see that the heads weren't moving. I only did the one small test with the lid off, moving the head rack arm to be sure it wasn't binding, even though it did stick for a moment near the edge of the platter(s). Beyond that I don't want to risk doing more that might damage the heads or platters if they aren't already. Of course, I can't know for sure that there isn't something bad somewhere else, but I'm trying to be optimistic.

I am considering buying another donor drive to try swapping another head rack assembly, as well as swapping the PCB again. Until then, any other suggestions will be greatly appreciated.
(fwiw, Greece is a place I'd love to visit some day.)

Thanks to all for the help!
-JT


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 Post subject: Re: Head stack doesn't move
PostPosted: March 8th, 2023, 23:06 
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Joined: March 17th, 2022, 21:24
Posts: 48
Location: Melbourne
You made some bad mistakes, that I don't need to repeat to you like a parrot.

Because you started to do these things yourself without success, at least swap the HSA back to the donor drive and see if the donor drive spins and still works.


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 Post subject: Re: Head stack doesn't move
PostPosted: March 9th, 2023, 0:16 
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Joined: December 1st, 2014, 0:07
Posts: 8
Location: America
Well, this last reply from SirForensic was clearly not helpful. I've had two polite, professional, and helpful replies, a neutral unhelpful one, and then this one which verged on insulting. I've admitted I'm having to do this myself simply because of the high cost, not because I wanted to do it or thought it would be simple. And I did go to a professional service first, which is why I'm here!

That said, I certainly didn't expect unhelpful replies here that were trite and condescending, so I'll move on and look for help elsewhere.
-JT


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 Post subject: Re: Head stack doesn't move
PostPosted: March 9th, 2023, 1:14 
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Joined: September 8th, 2009, 18:21
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Location: Australia
@SirForensic was telling you to do what the pros usually (?) do when a headswap fails, and that is to return the donor headstack to the donor drive. If the donor drive no longer works, then this would suggest that you damaged the heads. Otherwise, if it still works, then you can have some confidence in your technique.

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 Post subject: Re: Head stack doesn't move
PostPosted: March 9th, 2023, 4:33 
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Joined: January 28th, 2009, 10:54
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Location: Greece
True that, nothing condescending on SirForensic's comment.
We do that a lot, when something doesn't work on a headswap, we put back donor heads to donor drive and see if that works. If it doesn't, that would mean either incompatibility, media damage on the patient drive that caused heads' destruction, or poor technique during the swap.

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 Post subject: Re: Head stack doesn't move
PostPosted: March 9th, 2023, 4:47 
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Joined: January 28th, 2009, 10:54
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JTT wrote:

I am considering buying another donor drive to try swapping another head rack assembly, as well as swapping the PCB again. Until then, any other suggestions will be greatly appreciated.


You don't need to swap the PCB again.

My advice:

Buy a couple more donors. It would be great if you can find cheap donors with the same model as your patient. They don't have to be in pristine condition, but make sure they're not been opened before and they can detect in your system. If you can't find cheap donors same as your patient drive, you can choose some similar drives, like ST2000DMxxx or ST3000DMxxx. They'll have different number of platters/heads so you'd need the appropriate tool.

Open them up, remove the heads, and put them back in.
Check if the drive is still detected.
If not, your technique/tools/equipment is wrong.
If yes, try that again to rule out random success.
If you succeed again, then buy a new donor for your drive matching as much as you can and try another swap.

If you succeed, you should get your drive to spin up, not click at all, to stay spinning and the heads to start calibrating.
When you get to that point, you must connect COM port to terminal and tell us what it says.
Then, you'd have to have a ready-to-go solution to image your drive to a new one, preferably without switching the drive off.

Good luck!

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