Hello all,
this is my problem; perhaps somebody can help me.

Thank You very much in advance.

I own an old (year 1999, I suppose) HDD SEAGATE U4 ST38421A (8.4 GB).

It was used as a Master HDD.

Suddenly it made a metallic strong short noise .

Then I cannot no more access to it from Windows XP .

I turned off the PC and then on: the HDD started making a metallic noise like the one here:

http://it.youtube.com/watch?v=wMk58s8ibh0

About this HDD, the video's Author says that it's a logic problem. I think no; it's a hardware problem (or not?).

Anyway, my HDD turns itself off automatically after a short time.

Then , carefully, in a clean area (not a "Clean Room") I opened the drive.

It has two platters and 4 Heads.

The upper platters surfaces seems to be in good conditions but I noticed something "strange" looking the lower platter head.

Then I carefully dismounted the Heads Stack and I discovered that the lower head is broken (it was no more in the correct position on its arm and had its 4 electrical conductor stripes broken).

The Heads Stack electrical connector has written this:

"N-F 99 25 2 SG61476-300".

Instead, the HDD has written on a silver label on its "gum" body:

SEAGATE U4 Model ST38421A;

P/N: 9M9004-034;
Configuration Level: A_4331;
Configuration Code: UDQ-01;
S/N: 6BD04LZ5;
Firmware 6.01;
Date Code: 0007 Site Code: SZ.

(Made in China)

Now, my desire is (a day) try to recover some files on this Drive but:

1) I need new Heads from a Donor HDD and I don't know if the Heads Stack is the same on all U4 ST38421A Drives. I asked to SEAGATE but no replies... .

In fact I have found another "ST38421A" but it's Part Number is a little different: "9M9004-304", not "9M9004-034").

2) I cannot see the lower platter surface conditions (this to investigate scratches; perhaps a "new head" can be damaged by a scratch; perhaps there is a manner to evite it reducing head movements but I don't know if it's possible to start the drive with heads not on landing zone or with reduced movements).

Of course I will decontaminate the drive in a "Clean Cabinet" and carefully install "new" (= used but working) heads.

I am asking myself also if is not possible to read part of data using only 3 heads (when one head is electrically disconnected does the drive work?).

Is this a "simple" Drive to repair without important scratches on surfaces? Is it true that opening a Drive in a non "Class 100 Clean Room" Data is lost (I think no because the Data is related to magnetism)?

Thank You .
Kind regards.

Mark

If the surface with the damages contains the service area, changing the heads will not do any good as the new one will immediately be destroyed again. If it has no vital data on it, there would be no good reason for swapping it.
A class 100 clean environment is defined as less than 100 particles of 0,5µm per cubic feet, so it's not more than a matter of stochastics whether a particle will sit down right under a modern 2,5" drives GMR head and rip it off. So the answer will be: a ISO class 5 clean room is not strictly necessary, but highly recommended. Or a clean cabinet of the same quality, which seems to be more appropriate for people who don't work 8h a day on HDDs.
Those crazy case modders who now switched to hdd modding prove that also ISO class 9 may be enough to run a 100+ gig HDD for much more than hours. No option for DR, sure.

Thank You, Shaun for Your reply. Anyway, as I explained, I don't know the exact situation about scratches on the lower surface. Another fact: the lower head in the original Heads Stack, as I wrote, it's broken. Then I suppose that I need another Heads Stack. This would be not necessary if I can reinstall original Heads Stack with only 3 heads working (a person said to me that this is not possible: all 4 heads have to be electrically working). I think that the first thing it's to understand if all "ST38421A" Models use the same Heads Stack (but I think that, also for tolerances in building, it's better to find the same kind of HDD as Donor).
Regards,

Mark