Hitachi 1TB, Bad Motor, stuck head?

[JoeNicholls]

I have an Hitachi 0F10383 (1TB) for a customer that will not go ready, but having a bear of a time finding a donor drive. I have not opened the drive yet pending getting a donor. Is there anyway to determine if it has a bad motor verses a bad head? I put an oscilloscope on the 4 motor leads and see the expected pulses, which quit after 5 VERY faint clicks. The drive is very quite and not vibrating, which make me think the motor is not turning, but not having done an Hitachi before i am not sure how quite they are. Alternatively any advice on where to probe the PCB with an oscilloscope to see it data is streaming from the heads as it tries to read it's negative track?

Thanks,

Joe

[drc]

IMO you do not have enough of an understanding of how these work to be working on them

[jono-ats]

PCB swap will tell you if it is a motor problem. If it's a mechanical issue or something you are not familiar with, you should do what is best for the customer, IMHO.

What's the bandwidth of the scope you are using, and is it analog or digital?

[JoeNicholls]

The scope is a cheap dual channel 50MHz digital. I use it main to see if the presence of signals exist and not really get into measuring actual pulse widths (or frequencies). The customer stated that he got the drive to work once after it failed by doing "the frisbee movement" (quickly snapping the drive around in the horizontal plain). I think he heard my under the breath gasp. I have not been able to find a donor drive yet to swap the PCB. My next step is to use the ohm meter trick to test the pre-amps.

My main function is as a computer/cellphone forensic examiner and I have done a large number of software recoveries of corrupted disks, but I admit I am still a novice at disk drive internals and head stack swapping.

[drc]

A 1TB Hitachi with client data is not a good starting point for learning about internal work, especially if it involves moving platters

I really mean no offense with this, but as it is relevant to another current discussion (myharddrivedied-com-data-recovery-training-t18621.html) would you say that Scott Moulton's Infosec course did not adequately prepare you for this type of diagnosis and work? What about your IACRB "Certified Data Recovery Professional" certification?

[JoeNicholls]

As with anything, classroom and book learning will take you so far, and then real world experience becomes the teacher. In my forensic work, learning FTK and EnCase was necessary, but only after doing actual investigations and court room work does it all come together.

Doing practice head stack swaps and platter swaps in the InfoSec classes was invaluable in not only trying different techniques, but also in teaching how easily you can totally screw up a set of platters if you don't know what you are doing. Which is why I have not cracked open this disk drive. I want to do a PCB swap first.

[jono-ats]

A 50 Mhz scope has 1/20 to 1/40th of the bandwidth needed for modern drive analysis. Not that it can't yield some qualifiable (as opposed to quantifiable) info . . .

I don't think folks are going to readily share PC test points, but you may be able to learn a lot by comparing your working donor to the patient drive.

I wouldn't poke around the preamp with a VOM, as I have heard from others that it is possible to destroy a preamp this way.

Bearing or motor issues happen from time to time with these.

Wait a bit and someone will be along soon to give you advice about the TVS.

[BlackST]

You won't see anything with that scope except on some lines of hda connector. Need DDA + diff probe. And if there was stiction, knowing hitachi media and organisation, you'll face most probably other problems.

[fzabkar]

Is there anyway to determine if it has a bad motor verses a bad head? I put an oscilloscope on the 4 motor leads and see the expected pulses, which quit after 5 VERY faint clicks. The drive is very quite and not vibrating, which make me think the motor is not turning, but not having done an Hitachi before i am not sure how quite they are. Alternatively any advice on where to probe the PCB with an oscilloscope to see it data is streaming from the heads as it tries to read it's negative track?

If you place your ear against the drive's housing, it should be obvious if the motor is turning. In any case, if you hear clicking immediately after applying power, then that's "spin buzz", not the voice coil actuator.

This site has an analysis of good and bad spindle motor waveforms:
http://nazyura.hardw.net/000004.htm

The VCM waveforms at the above site should be accessible at the preamp connector. Look for two adjacent pads with heavy tracks. Alternatively, you can monitor the VCM current via the array of parallel connected current sense resistors near the motor controller IC. Be sure not to ground these resistors via your CRO leads. The second resistor array senses the spindle motor current. One end is grounded. Look for pauses between each spin buzz. That should confirm whether the motor is stuck or spinning freely.

Here is the datasheet for a typical motor combo controller:

L7250, SMOOTH, spindle motor + VCM controller, ST Microelectronics:
http://wandrew.regruppa.ru/PCInfo/TechDoc/L7250(Smooth).pdf
http://www.datasheetcatalog.org/datashe ... Xyuswx.pdf

As for preamp test points, it's fairly easy to identify the supply rails and VCM terminals. The remaining pins are probably differential signal pairs.

I wouldn't poke around the preamp with a VOM, as I have heard from others that it is possible to destroy a preamp this way.

This thread should dispel that nonsense:
samsung-hdd-hd753lj-dead-t15374.html

Wait a bit and someone will be along soon to give you advice about the TVS. :o

Why do you think it's a TVS issue? :?

[thatdellguy]

...

funny-surgery-cartoon-comic-strip1.JPG (26.78 KiB) Viewed 10804 times

[rameez]

lol

[chinopk]

nice picture, the patient did't got anesthesia yet !

[poehere]

Nice job! lol

[jono-ats]

I wouldn't poke around the preamp with a VOM, as I have heard from others that it is possible to destroy a preamp this way.

This thread should dispel that nonsense:
samsung-hdd-hd753lj-dead-t15374.html

In my cursory reading of that same link, more than one pro disagrees with you!

Wait a bit and someone will be along soon to give you advice about the TVS.

Why do you think it's a TVS issue?

Apparently, you don't get the joke . . .

[irs]

@ thatdellguy: nice cartoon!!!

[mr_spokk]

He he, nice one

[zebong]

heheh nice story

[fzabkar]

nice picture, the patient did't got anesthesia yet !
:lol: :lol:

They're doing a hot swap.

[fzabkar]

I wouldn't poke around the preamp with a VOM, as I have heard from others that it is possible to destroy a preamp this way.

This thread should dispel that nonsense:
samsung-hdd-hd753lj-dead-t15374.html

In my cursory reading of that same link, more than one pro disagrees with you!

Theirs is an ingrained misconception resulting from years of disinformation.

Wait a bit and someone will be along soon to give you advice about the TVS. :o

Why do you think it's a TVS issue? :?

Apparently, you don't get the joke . . . :D

Ditto.

[jono-ats]

Theirs is an ingrained misconception resulting from years of disinformation.

Your statement strikes me as a bit too "sure" for someone who says he does not "do" data recovery . . .