I can read only with a head WD5000LMVW

[Jaime]

Hello,
I have a problem with a hard drive western digital WD5000LMVW, with embedded USB in PCB.
I have changed the PCB with USB by compatible PCB with SATA connection and swapped the ROM.
When power is ON, is recognized quick and OK, I can enter in normal mode.
I can make backup all SA. (modules and ROM)
This hard disk have 2 heads, I checked heads and it is ok.
I checked the modules of SA and all modules was ok.
I can read with the head 1 all sectors, but when I try read any sector of the head 0 give me error UNC.
I think that the head are ok.

Somebody can I help me?

What can I do?

Thank and happy new year.

[DataMedics]

The head is bad, need to change them. Head test on WD is notoriously unreliable. If you can read from any head, it rules out SA damage and other issues.

[Jaime]

Thank datamedic.
You had reason, I swapped the heads and I could to read all data from head 0.

Thank you very much and regards.

[Maxim_TS]

Hi Jaime and DataMedics,

I would like to explain why it happens: head could be strong enough to read and write in SA, but too weak to work in User Area.
That's why it pass the head test.

Jaime, next time you can change the head map in RAM first, enabling only the good head in a map, send Soft Reset, reenter in utility, set the original head map, and I think you can read the data by both heads.

[DataMedics]

Source of the post head could be strong enough to read and write in SA, but too weak to work in User Area

I've always wondered about this phenomenon and the reason behind it. Is it that the SA data is less dense than the user tracks?

[Maxim_TS]

DataMedics, Yes, exactly.