WD Mystery Case

[Jared]

I'm posting this here just in case my customer follows the forum.

I've got a case here which has me truly baffled. I've handled a lot of similar cases, but this one I just can't figure out.

Drive came in it was head stuck. I freed the heads up carefully.
On power up the drive fully ID's shows capacity everything. I backed up all modules and tracks without any issue.
When I try to read a sector it gets ABR error instantly.
Tried editing head map in RAM but it would go unstable as soon as I soft reset it.
Checked all modules in directory and all important modules pass check for both head 0 and 1.
Did a heads test and found H5 to be faulty.
Replaced heads with donor ones, and all heads pass test now.
I've confirmed that all heads can both read and write data.
However, I still get ABR error on any attempt to read sectors like there is a translator issue.
I've tried subbing out the service area regions.
I've even completely moved the SA from heads 0 and 1 to heads 2 and 3.
I've tried regenerating the translator
I've tried rebuilding the P-list, then again rgenerating the translating.
I've done the slow responding fix, and tried disabling things in module 02
I've tried pretty much everything I can think of and no matter what I can't get this thing to read a sector.

Any ideas? Any WD masters who'd like to take a quick look remotely? I've already had another tech look at it via TeamViewer and he's stumped too.

I'm certainly willing to throw some hard cash to whoever can solve this one. At this point I care more about figuring this out than I do about the money from the case.

 

[Jared]

OK, I think I may have figured out what's going on here.

I finally took an opportunity to look at the sliders under a microscope and this is what I find:




I guess the difference is small enough that it can access the SA just fine, but not the user area.

 

[Sam]

Jared,

Are those dots contamination spots or difference in the topology of the slider pattern?

 

[abedalkareem]

[post]6732[/post] OK, I think I may have figured out what's going on here.

I finally took an opportunity to look at the sliders under a microscope and this is what I find:

interesting :?: :!:

 

[Jared]

OK, mystery solved. It was the heads in the end that turned out to be the issue. I guess that silly dot is a pretty big deal.

What's really mysterious is just how far off the donor I finally used was that worked.

Patient:
WD20EARS-00MVWB0
HHRNNTJCH
Jun 2012
Malaysia
Preamp Vendor: 0001
Preamp Revision: 0001

Donor that worked:
WDEARX-00PASB0
DARNHT2MAB
Jul 2012
Thailand
Preamp Vendor: 0000
Preamp Revision: 0005

The only reason I even tried it was because I had the donor here for another case which is a heads killer (already killed 3) so I figured it wouldn't hurt to try them before I kill them off.

 

[Amarbir[CDR-Labs]]

OK, mystery solved. It was the heads in the end that turned out to be the issue. I guess that silly dot is a pretty big deal.

What's really mysterious is just how far off the donor I finally used was that worked.

Patient:
WD20EARS-00MVWB0
HHRNNTJCH
Jun 2012
Malaysia
Preamp Vendor: 0001
Preamp Revision: 0001

Donor that worked:
WDEARX-00PASB0
DARNHT2MAB
Jul 2012
Thailand
Preamp Vendor: 0000
Preamp Revision: 0005

The only reason I even tried it was because I had the donor here for another case which is a heads killer (already killed 3) so I figured it wouldn't hurt to try them before I kill them off.

Hello jared ,
i am zapped again even preamp vendor and preamp rev were not matching and the heads worked great man ,Was it the slider topology that matched and it worked ?

 

[Bankole Oladoja]

Interesting.

 

[Jared]

":2hm91el6][post]6758[/post] Was it the slider topology that matched and it worked ?

To be honest I didn't actually look at the sliders of this set. I never expected it'd work, I just figured I'd give it a shot before ruining the heads on another case that's almost certainly a lost cause. I'll probably take a look at them under the microscope after I'm done imaging this case. It's already 95% imaged, but one head is reading very slowly and has a lot of read errors.

I'm thinking that the preamp vendor code may be site specific. So since one drive was from Malaysia and the other Thailand they may designate the vendors differently. Though I can't explain why it'd work being such a different revision.

 

[pclab]

[post]6732[/post] OK, I think I may have figured out what's going on here.

I finally took an opportunity to look at the sliders under a microscope and this is what I find:


View attachment 1

I guess the difference is small enough that it can access the SA just fine, but not the user area.

Hi Jared

One question: for your photos you use the microscope light, or you have another light?
How do you take such clear photos?
Thanks

 

[Jared]

I thought those photos were actually really blurry (I was holding the heads by hand when I snapped it). I generally hold a led flashlight at an angle to shine across the slider surface and bring out the contours.