WD5000BMVV HDA causing failure of pre-amp in donors?

[cheadledatarecovery]

Some unusual symptoms after head-swap on this:

Patient: WD5000BMVV-11GNWS0

Sustained physical shock, opened HDD, and there is clear misalignment of a head. Replaced head assembly with donor and changed PCB to SATA version. On power on drive clicks does not enter ready. Changed head map to 1,1,1,1, soft reset, drive initialises with a fair bit of noise and gets to RDY. Can't get drive ID, use a database LDR for permanent overlay. Loads OK. Try to load DIR, then drive entered BSY. It was necessary to power off.

Now the odd bit:

On power on the drive no longer spins up and goes to ERR. If I isolate the PCB to HDA connector then the HDD spins up, no clicking, and enters RDY. I can enter kernel mode and interact with the PCB (alter ROM etc.) i tried a few times, changed ROM settings etc, but the same results each time. I checked all the PCBs used and they are fine and initialise other HDDs OK.

Finally I swapped the donor heads back into the donor and the fault was replicated - no spin up when PCB was connected fully.

I tried with a second donor HDD and the same fault has occurred. I presume that in each case the pre-amplifier has become damaged?

Thoughts and comments welcomed,
J

[fzabkar]

Measure the preamp supply voltages at J1.

[cheadledatarecovery]

Thanks,

Voltages as follows:

E10: 2.66V
E13: 0.04V
E56: 5.1V
E63: 2.66V

0V at E13 would suggest pre-amp failure. This fits in with the symptoms. What I don't understand is what is causing the pre-amp failure, particularly as for the first time the drive gets power on with donor heads it responds normally, and then only after a power off-on the pre-amp fails.

I have a feeling this is not worth spending too much time on for the purposes of the recovery job; before the pre-amp fails it was not possible to initialise from head 0. When altering the head-map to initialise from head-1 the drive just about got to RDY after about 60 seconds and it sounded very scratchy indeed. There is most likely media damage, particularly given that the original cause of failure was physical shock whilst powered on and a head was twisted (image of failed heads below).

J

[microsoftengineer]

+1 Media Damage