WD 12TB myBook HDD PCB 004-0B14714 damaged with 19V

[markhoff]

I have an external HDD which is supposed to receive 12V, but I happened to plug in the 19V. now the HDD is not even spinning up. I disassembled the HDD enclosure and removed the PCB. measured the suspected parts and found two of them to have 0 ohm resistance in both directions (red-circled on the picture). "Z4" and "74". I am sure at least one of those is a TVS diode, Z4 could be a (broken?) zener diode.
Which part should I begin with to remove and check if the HDD works again with 12V?
Anybody knows of a PCB repair shop preferrably in central Europe?

Attachments

[fzabkar]

"Z4" would be the 12V TVS diode. I would remove it. Also check the tiny fuse nearby.

"74" would be a Schottky rectifier. It should be OK, unless the 19V supply was reversed in polarity.

[Lardman]

Laptop adapter rather than the drive enclosure's?

Follow Fzabkar's advice , start with the tvs and the fuses. Hopefully you'll be lucky and there's no other damage. I don't know of any pcb only services, best place for a quick bit of microsoldering tends to be your nearest mobile phone repair shop.

You get a full service from a DR pro and pricing reflects that.

[markhoff]

thank you very very much for your answers! I finally decided to have the PCB repaired professionally by a electronic repair company in Romania. Will keep you guys posted about their assessment and repair costs.

[markhoff]

Very bad experiences....the repair shop in Romania was not able to repair the drive, or did not have much knowledge. After having a hard time getting back the PCB, I sent entire unit to HDDPCB.eu - a shop that looks legit, but does not do anything. I finally managed to get my unrepaired drive back, with a lot of effort. I will order a replacement PCB and erase the drive.

[fzabkar]

If the problem was confined to the TVS diodes and fuses, then the repair should have been straightforward. However, I have encountered one thread a Tom's Hardware where the was additional damage to the LX8237 IC which constitutes the second level of protection.

http://www.hddoracle.com/viewtopic.php?f=100&t=1615&p=22339#p22339

https://forums.tomshardware.com/threads/used-old-psu-cables-on-34tb-of-drives-and-they-are-no-longer-recognized.3739967/

[markhoff]

I ordered a replacement PCB and found out by comparing with a multimeter that one of the tiny fuses near the Schottky diodes was blown on the original PCB.
instead of replacing only this fuse I went to a shop to have the 2 firmware chips transferred to the replacement PCB by soldering. With this replacement PCB the HDD spins up again and the data is readable.
The price of the solder job was about EUR 70. I have the contact details of the shop in Vienna if somebody needs it.

Please, never ever use the services of hddpcb.eu - I did and got very disappointed.

[fzabkar]

You probably only needed to bridge the fuse.

[hdmrz]

I have the contact details of the shop in Vienna if somebody needs it.

Hi markhoff,
I have a similar issue with the same drive and PCB. Would you mind providing the contact details of the shop in Vienna? Thank you.

[fzabkar]

Remove Z4 with flush cutters and retest for shorts.