WD Black unable to read from 2 heads

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HEX
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WD Black unable to read from 2 heads

Postby HEX » 01.04.18, 10:35

Hello,

I have, an unusual, problem with the WD disc, I think.

The patient came after an electric overvoltage.
The symptom was that after changing the PCB, the platter didn't spin up, it only started after the separation of the heads connector.
It turned out that there is a short circuit on the preamplifier pins, which is why the drive does not start.

After repairing the electronics and replacing the head with the donor's disk, it was not possible to calibrate the disk for work, no matter if it was run on the original adaptives or on the map of the heads from the donor's disk.

After a few days, a compatible donor was found.
And here are interesting things.

Head number 1 is not able to read SA, it is disabled in RAM for the time of booting.
Heads 0 and 2 gived data in 100%.
Heads 1 and 3 read a few sectors, then go to the illegible sector and over and over again.
The drive before the failure was definitely working, it also confirms SMART.

I attach screenshots as it looks.
Do colleagues have an idea about what the problem might be?
After returning to the donor, the heads work without any problems.

Model: WD6401AALS-00L3B2
DCM patient: HHNNNV2MAB
DCM donor: HGRNNV2MAB

Image
Image
Image

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DataMedics
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Re: WD Black unable to read from 2 heads

Postby DataMedics » 02.04.18, 18:26

Most likely the heads aren't a great match. Perhaps the microjogs are too far off.

If at first you don't succeed, try try try and try again.

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HEX
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Re: WD Black unable to read from 2 heads

Postby HEX » 03.04.18, 11:46

That's what I'm afraid of...
Generally it is difficult to find a matching donor for him.
The heads from the previous donor didn't want to calibrate at all.

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Blizzard
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Re: WD Black unable to read from 2 heads

Postby Blizzard » 03.04.18, 15:57

It's just a guess, but you might want to put the donor heads back in the donor and scan head 1 & 3. Maybe your head tool is causing a problem?

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HEX
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Re: WD Black unable to read from 2 heads

Postby HEX » 12.04.18, 18:53

No, it's not the bad or fault of the tools.
The heads were transferred to the donor and then I made a 100% copy ...
It looks like an incompatible set of heads as DataMedics suggested.


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