Question Help with identifying TVS diodes and Zero Ohm resistor

Sep 16, 2020
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Hi everyone, anyone

I've got an 8Tb Seagate Barracuda drive here that came in an external enclosure. I was cleaning my office and unplugged everything then when plugging it all back in I accidentally plugged in a higher voltage plug and it has stopped working (no spin-up, no blinking light, nothing). I purchased a new enclosure, tore the drive out of the enclosure it came in and put it in the new enclosure. No dice (just a blinking light on that enclosure). From what I've been reading it's highly likely its either the 12V TVS Diode or a Zero Ohm resistor. I'm sure it could be something else but my gut tells me it's the 12V diode (since it makes sense it would blow when being hit with the 24V accidental plug). I'd like to snip and or blob it and see what happens (like I've read is occasionally possible). The content of the drive is not incredibly important as I do have other backups of the important data on it but I'd like to retrieve what I can, if I can. I have managed to remove the PCB from the drive to try and determine what parts are what and, well, that's where I am now and why I have come to ask for some help. I have included some photos for your reference, I haven't marked them up in any way.

I have also included the part number for the PCB from the "bottom" of the PCB and have a secondary question about this. I have found a site (referenced elsewhere at Tom's Hardware) where I can get a replacement PCB for this drive but the number does not match even thought it is for the same model number HDD. My question is since the PCB is for the same model number HDD but doesn't match the part number for the PCB it came with, is it possible it could still work for me? I understand I'd have to switch out the one chip that seems to be matched with my particular HDD. The part I have found is here: https://www.hdd-parts.com/19062403.html . You'll see it "looks" very similar. I looked closely and there are some differences. I wonder if with the swapping of the certain chip if this would do the trick.

Here are the photos:






I will admit that I have not checked anything with a multimeter, I do have one but not the skills to use it. I will be doing some reading up on that right away to gain some of those basic skills. Thank you for any help given.

Frazer
 

Mtop

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Nov 21, 2019
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Zero ohm diode is a fuse! Diodes read resistance in one direction and a short in the other.(a short in both directions is bad) If measuring on the circuit board results may vary due to other components in the same circuit.
But if you removed enough to see the platters and were not in a clean room then trash the drive and save youself alot of time.
 

vov4ik_il

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Mar 23, 2020
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To answer the first question, I marked input 0-Ohms and TVS Diodes. I am skeptical about your assumptions but it does not hurt to try.


Check the 0-ohms for continuity, the diodes are sturdy and would not normally fry prior to getting the resistors fried. To do it, set your multimeter to resistance mode, would be 8 or 9 in the image below. Now:
(Step 1) get your probes together and obtain a reading (ideally "0"). Then,
(Step 2) firmly attach a probe to both ends of the resistor (one each side, no matter what end to which probe) and obtain a reading.
(Step 3) compare the readings, if not identical, the resistor pair is bad.
There is a good chance that the PCB is coated with conformal coating, if so, remove it with proper solvent, before making measurements.


My question is since the PCB is for the same model number HDD but doesn't match the part number for the PCB it came with, is it possible it could still work for me? I understand I'd have to switch out the one chip that seems to be matched with my particular HDD. The part I have found is here: https://www.hdd-parts.com/19062403.html . You'll see it "looks" very similar. I looked closely and there are some differences. I wonder if with the swapping of the certain chip if this would do the trick.
The part you have linked is a flash memory IC that contains the firmware. Replacing it with the same chip will not give you the same content on it. While it might, it did not necessarily get damaged. Replacing the whole board part by part is a lot of labor and not free. While you can replace the whole controller board, this HDD must have something very expensive on it for you to go that deep. If you find out that it is a bad resistor pair, replace them, if not I would not waste any more time on it :)

P.S. There is no such a thing as
Zero ohm diode
unless it is baked.
 
Last edited:
Sep 16, 2020
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Thank you everyone for your answers. Once I can obtain some readings I'll get back to this thread and update.

Quickly though:
  • I have not disassembled the drive to the bare platters, just taken the board off.
  • I too am skeptical of my intuitions.
Thanks again, I'll be back :)
 

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