[Diagnosis Help] Seagate ST3000DM001 - PCB Power issue

[Zebananos]

Hi everyone,

I am a student currently working on a personal project for educational purposes. I've recovered an old Seagate Barracuda ST3000DM001 (P/N: 1E6166-570) that is not working, and I am using this as an opportunity to learn basic electronic diagnostics.

To be completely transparent, I have no formal electronics training. I am working with an old multimeter and an old oscilloscope, and I am trying to learn how to troubleshoot a PCB. I have attached a few photos of the board.

Here is what I have observed so far:

Power: 12V and 5V are correctly reaching the PCB via the SATA connector.

Motor: The motor does not spin at all (no sound). When I probe the 3 motor pins (downstream from the SMOOTH chip) with my oscilloscope, the signal remains flat while the PCB is powered.

Components: I tried checking the 12V and 5V TVS diodes with my multimeter. They appear "OK" based on my basic readings, but I am not entirely confident in my methodology. Is there a better way to test them, perhaps using an oscilloscope?

What are the "must-check" points on this specific model?
Are there any common failure points known for this board that I should inspect with my multimeter?
Should I be actively hunting for shorts?

Any guidance or tips to help me progress in this diagnostic would be greatly appreciated. Thank you in advance for your help and for your indulgence with a complete beginner.

Best regards,
Zebananos

Attachments

[fzabkar]

What voltages do you measure across each of the two TVS diodes?

[ora]

Next to the SMOOTH chip, there are large gray coils with two terminals. They should show something, about a volt or more. If all coils show 0 volts, it's worth checking whether the voltage is reaching the TVS diodes. Repairing such boards usually ends with removing the diodes shorted by voltage surges and replacing the burnt-out resistors near the power connector with jumper wires. If the drive still refuses to spin up, the board is usually thrown in the trash and replaced with a working one from a donor drive. No one thoroughly examines these boards, so you'll have to be the first.

There's also an 8-pin chip on the board; this is a ROM. One of its contacts should show 2.5 or 1.8 volts. If the contents of this chip are erased or damaged, the drive also won't spin up.

Judging by the obvious mechanical damage to the board (one of the inductors is broken), this board will never work again - perhaps the contacts under the smooch chip were broken by impact.

I'd also like to point out that these boards have very few components. You can check the capacitors for shorts and measure the resistors (ideally, using another similar, working board as a reference). However, they rarely fail. If the SMOOTH chip had accessible pins, you could measure their resistance relative to a similar chip on another, working board. But that's not the case.

[fzabkar]

Judging by the obvious mechanical damage to the board (one of the inductors is broken), this board will never work again

I beg to differ. The board will still work if the coil is not open circuit.

The group of 3 coils are associated with buck converters for Vcore and Vio. The 6R8 coil and the associated diode (E0/U4) constitute the negative supply (-5v) for the preamp.