Heads not unlatching - ST1000DL002

[deftrue]

Hello community,

I've got a Barracuda LP - ST1000DL002. It has a very particular head map - Three platters, three heads (H1, H3, H5). I found what it seemed to be a good donor, with same physical head map. Donor works OK, patient has a small notch on top surface which I think I can overcome and make the drive go ready at least for a while.

Funny thing: Donor heads on patient drive wouldn't unlatch. They stay parked, emitting a faint "sh" sound 11 times until spindle stops. Swapped again heads to donor, which again callibrated and went ready.

Patient drive with patient heads will spin up, unlatch heads and click (and also beep at some point) 11 times.

What could be the reason for such behavior? PCB is a match and of course I'm using patient ROM, having tried both PCB's. Both drives have S/N starting with W1V, both China SU. Date codes may differ a bit: 11324 and 12187 - it may explain it, but I just want to be sure (as sure as I can be in such matters, you know).

Regards

[dmarques]

My guess is that it can be 2 things: preamp or MCU.

Check both.

[deftrue]

Hello dmarques, thanks for your answer.

Heads are working on donor drive (i.e., drive with its native heads is working), so I think that discards preamp problems - I tried twice, before and after first try on patient HDA, and I reassembled the donor and found it was still working as well. Also, I've tried donor PCB with patient ROM with same results, which I believe discards MCU problem. Don't you agree?

EDIT: As for my experience, preamp problem usually show up as totally unresponsive and non-moving HSA. This case is slightly different, since heads emit short and faint noises, but they are not leaving the ramp.

Cheers

[dmarques]

From what I understood, donor heads are working on donor drive right? But they don't work on patient, right?
Even if preamp is incompatible, on most of the cases, heads don't get killed, they simple will not unlatch.

Regarding PCB, have you checked if MCU's are the same?
Also, have you tried donor PCB with donor ROM on patient? Patient ROM could have problems also (which I don't really think).