Hitachi ARM heads transplant READY, but no ID compatibility?

[ThomasH]

Well, for the umpteenth time, on a 2.5" ARM drive with bad heads, after xplant, I get the drive to show DSC/DRD, but it doesn't show model/sn.
Start the utility as pcb only, close the session, re-enter utility, and it shows model/sn, and can read modules well, but no data access. (sometimes at this point, I have had data accessible, but usually not still, and not in this case).

Once, on a different case, I let a drive sit for a week with 'incompatible' heads, and it magically started up with no extra work, despite having tried everything before, which makes me hopeful there's a way to adapt these 'not-compatible enough' heads...

Transplant heads back to donor and it's ok, and donor works perfectly.

Matching MLC seems to help, but isn't always a sure bet. I will say the ones that worked best were very close to the same build month+day, but I can't say I do enough to be sure how important that really was. Current drive I'm working on is same MLC, 2 months difference. Only ID's using above method, but has no client-data access, just modules. I have always kept the magnets with the headstack (easiest with Hitachi).
Perhaps matching the upc sticker opposite SATA/power connections to the left of the s/n sticker (barcode)?
P/N? Certain characters in the S/N?
I believe I've had success without matching MLC, but looking at that case, the barcode is a match...I guess that's where I'll start. No idea if it was coincidence.
Anyone pretty please know what to really match on these, or have a solution?

[AJ2008]

The base code seems to have some relevance in compatibility also. Maybe would be an idea to start new thread for compatible head change on this model including all details of patient and donor, maybe with many good results to look at some pattern can be identified

[ThomasH]

The one I still have both client and donor to that was a perfect clone to reference was a VERY close match to pretty much everything on the label...but here's the specs that did vs didn't match:

donor matches: model, p/n, MLC, side barcode, and the first 3 of serial# match too.
client is 15MAY11. Donor: 21MAY11....AND they both have matching Lenovo p/n.

The circular sticker on the bottom of drive has a matching top line, (0J13623). The other numbers on the circular sticker don't match, but one is close: 2BA vs 2B9. The others are way off. Don't know what these numbers are, or if matching that top number might help. UPDATE: (Found the 1st donor that didn't match, and the circular sticker also has the same top line, so circular sticker probably doesn't matter). (Everything else on 1st donor was off (mlc, barcode, p/n)

client headstamp#: T7A-113 Donor headstamp#: H7A-216 ... just in case.

Not much help probably since so close in many ways, just mentioning.

[ThomasH]

Tried a few bar code + MLC matches from same month + 1month off, with no luck on a 750gb 4 head.
Maybe FW match, or the numbers on the bottom of the pins connecting to the pcb? Haven't had a match on either of those yet to try, but ...