on burning the PCB (chip on the picture, not a diode), can happen also some demage to the head' stack or to spindle motor ?

This is a common problem, I've had to fix lots of these.
Getting a replacement PCB and swapping the 8-pin chip at U12 should get the drive working again.
Hopefully nothing else is damaged, like the preamp or other components inside the HDA.

_________________
Death is nothing, but to live defeated and inglorious is to die daily.
Data Recovery Cape Town

exactly, it never happen to you? i am afraid to find it.

there is a way to test the pins with a tester, by ohm for example ?

All the cases I have had where motor controller is burnt (SMOOTH chip), the preamp has been OK. Just a new PCB and U12 swap and the drive is repaired.
But I have found that when the main controller chip is burnt (Marvell chip) that the preamp is often damaged, so it needs head stack replacement.

_________________
Death is nothing, but to live defeated and inglorious is to die daily.
Data Recovery Cape Town

I'm sure there is, but I haven't tried that procedure before. I think you'll find that some people say that you can easily damage the preamp by using a multimeter etc, but I'm sure there is a way to do it properly, I just don't know enough about it. I just use a process of elimination, which is normally quite accurate if you have the right tools.

Maybe someone else can offer advice....or maybe not. You know, 'trade secrets' etc.

_________________
Death is nothing, but to live defeated and inglorious is to die daily.
Data Recovery Cape Town

yep, that's sure!

the swap of 8 pin chip on U12 for what is needed?

Do as suggested above and save the data
Very rarely the preamp goes bad so don't bother

There are a few options, but I use a heat gun/hot air gun to heat the chip, wait for the solder to turn liquid, then swap it over. Obviously there are risks with heating up the PCB.

Yeah, you might as well replace the PCB anyway, because if you find that the preamp is gone (unlikely) you'll need a working PCB anyway on the road to recovering your data.

_________________
Death is nothing, but to live defeated and inglorious is to die daily.
Data Recovery Cape Town

thanks to all i will try to swap the chip and pcb.