This ext. drive WD10EACS-00ZJB0 doesn't power on. i had a closer look at the pcb and didn't see burned chip or similar. Xronis (rafaela) saw the HDD and told me that there is propably an error with the smooth chip.
if i have to change the pcb how can i read the ROM of the drive?
any other opinions would be appreciated.
i attached a photo of the pcb

thank you

You will need to reprogram the new PCB with some tools like (Atola, PC3K, SD tools..etc).

You can read the ROM modules from the platters using WDR-UDMA (US$150) or WD HD Pro, and then rebuild and reprogram the ROM on your replacement PCB. AIUI, it's a single-click procedure.

If you would like to narrow down the fault, then you can measure a few voltages.

Start with Q8 near them jumper block. That's probably the +3.3V supply.

Then measure the voltages at L2, L3, D3, L5, D4. One or more will be Vcore.

_________________
A backup a day keeps DR away.

i checked the pcb and the results are:
Q8 - 1,78V
L2 - 0.0V
L3 - 0.0V
L5 - 0.0V
D4 - 0,13V

as far as i know D4 show be 5V, L2,L3,L5 0,0V.
shall i intervene and make changes to the pcb?
thank you

I don't understand your measurements. For example, Q8 has 3 pins (plus a metal tab). Therefore you should measure 3 voltages, eg +3.9V, +5V, +3.3V. You should also see a Vcore voltage, probably +1.2V, at one of the inductors (Lx).

Are you measuring the voltages of your components with respect to circuit ground?

_________________
A backup a day keeps DR away.

Yes i am sorry. i didn't analyse it as i should.
the measurements are:

Q6 - 1PIN - 1.77 V
- 2PIN - 0.00V
- 3PIN - 1.11V

D3 - 1.35V

D4 - 0.14V
D5 - 6.52V
L2,L3,L5 shows 0,00V

thanks for your reply

I assume you mean Q8, not Q6.

Anyway, I have re-examined your photo and I notice that resistor R82 near the SATA power connector is missing. That would explain why you don't see +5V at the middle pin of Q8.

Install a wire link in place of R82 and then you may have a chance.

_________________
A backup a day keeps DR away.

Also confirm that R83 measures 0 ohms. R82 is associated with the 12V supply. Sorry.

_________________
A backup a day keeps DR away.