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 Post subject: Re: Hitachi HDD data recovery
PostPosted: June 12th, 2021, 2:38 
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Joined: June 4th, 2021, 3:17
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Location: syria
yes
but I accept the result because it changed from 20 ohm to 80 ohm
I considered this as an indicator


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 Post subject: Re: Hitachi HDD data recovery
PostPosted: June 12th, 2021, 13:46 
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Joined: September 8th, 2009, 18:21
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I confess that I don't understand the results. A resistance of 80 ohms still seems too low, but I have no working drive to compare.

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 Post subject: Re: Hitachi HDD data recovery
PostPosted: June 12th, 2021, 14:44 
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lets ignore the 80 ohms value and look that the changes is an indicator that it is really the preamp shorted on the patient drive, Because the 20 ohms value is the same when the two multimiter props touched each other and now on the donor drive it is different value.


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 Post subject: Re: Hitachi HDD data recovery
PostPosted: June 12th, 2021, 14:51 
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Location: syria
I want this confirming to know if i must continue in this issue or I must stop


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 Post subject: Re: Hitachi HDD data recovery
PostPosted: June 12th, 2021, 14:59 
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It does appear that the patient's preamp is shorted, but that would mean that the donor's preamp is measuring 60 ohms. That doesn't seem right either???

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 Post subject: Re: Hitachi HDD data recovery
PostPosted: June 12th, 2021, 16:50 
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fzabkar wrote:
It does appear that the patient's preamp is shorted, but that would mean that the donor's preamp is measuring 60 ohms. That doesn't seem right either???

this depends on the type of multimeter and the set measurement limit.


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 Post subject: Re: Hitachi HDD data recovery
PostPosted: June 13th, 2021, 4:45 
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What resistance do you measure if you reverse the probes (on both patient and donor)? It may be that there is a Schottky diode which is affecting the reading.

http://www.hddoracle.com/download/file.php?id=249&mode=view

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 Post subject: Re: Hitachi HDD data recovery
PostPosted: June 13th, 2021, 13:03 
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Location: syria
Here are the readings

patient drive:
4 ohms in both props direction (normal and reverse) and after subtract the the resistant of the multimeter wires

donor drive:
normal: 63 ohms after subtract the the resistant of the multimeter wires
Reverse: no value when the measurement limit is set to 200 ohms and
2.3k ohms when the measurement limit is set to 20k ohms


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 Post subject: Re: Hitachi HDD data recovery
PostPosted: June 13th, 2021, 13:10 
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Ah, that's a lot better. The diode (D) was being forward biased by your meter, resulting in a low reading. When it is reverse biased, the readings make sense. Sorry about that, I should have picked that up earlier.

That said, your preamp is dead. :-(

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 Post subject: Re: Hitachi HDD data recovery
PostPosted: June 13th, 2021, 13:27 
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Location: syria
so it is not DIY case and need more advance works
I assume that it need replacement of the preamp in clean chamber


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 Post subject: Re: Hitachi HDD data recovery
PostPosted: June 13th, 2021, 14:06 
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Yes, it requires clean room work.

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 Post subject: Re: Hitachi HDD data recovery
PostPosted: June 14th, 2021, 6:30 
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Joined: June 4th, 2021, 3:17
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I would like to thanks all who participates in this topic
and special thanks to fzabkar for his effort and patience


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