fzabkar
Here is nvram

nvram editing

Maybe I've introduced a red herring. Perhaps your model doesn't have a boot flag.

In any case I have no idea how a drive behaves when you edit the boot flag, but FWIW here is an article about a much earlier model:

http://www.disk-imager.com/data-recovery-blog/?p=1363

Later models appear to have FW boot flags of 0x81 and 0x80.

Maybe I'm barking up the wrong tree, but would it be worth retrieving the resources from a donor drive and comparing its PCB NVRAM and NVRC SA copy?

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A backup a day keeps DR away.

One head?

Doesn't look right

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PC Image Data Recovery
http://www.pcimage.co.uk

New!! HDD-PCB.COM for all your PCB and donor HDD requirements!

Yes, the HDT721016SLA380 has 1 head (section 4.1). The 250GB model has 2 heads.

Deskstar 7K1000.B and E7K1000 and CinemaStar 7K1000.B Specification:
http://web.archive.org/web/201212271121 ... ev3.01.pdf

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A backup a day keeps DR away.

I compare both the copies of Donor drive. i.e. the PCB NVRAM and NVRC SA copy. They have some difference in them, i am not an expert of this subject. Some more hint might help me resolve this issue.

Thanks

Yep, that's right.

I got confuddled by the post title "Re: Hitachi 500Gb - HDP725050GLA360 - Dead PCB"

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PC Image Data Recovery
http://www.pcimage.co.uk

New!! HDD-PCB.COM for all your PCB and donor HDD requirements!

Hello,
Could You Please Click Pictures of Your Native And donor PCB and Top Of Your Hdd Please for some of Us .As i suggested earlier a new thread would be wise you can still do it .We will do our best to assist

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Regards
Amarbir S Dhillon , Chandigarh Data Recovery Labs [India]
Logical,Semi Physical And Physical Data Recovery
Website-> http://www.chandigarhdatarecovery.com