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 Post subject: External HDDs - wrong power supply, need advice.
PostPosted: September 5th, 2019, 13:44 
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Joined: September 5th, 2019, 12:42
Posts: 5
Location: Canada
Good day to all;

I messed up huge and used an incorrect power source on 2(two!!) of my external HDDs recently. After some crying, I did quite a bit of snooping on the interwebs wrt to my misfortune and I found myself at a point where I could use some knowledgeable advice(pictures below).

Here's my side of the story, after wrong PS was used:
WD hard drive is a 4 TB HGST HD - was continuously causing new hardware found/disconnected in Win10 alerts. Only sound was present, no actual HD was seen at any point in device manager. (alerts may have been happening while wrong PS was connected, not 100% sure on this)
Took it out of the original case, plugged into a docking station - no effect. Tried a new external HDD case - same deal: no sound(neither win10 or HD spinning), no signs of life. No lights of any kind.

Seagate HDD is a 5 TB HD, some very faint clicking noise when power connected, did not sound like drive was spinning or trying to spin.
Same deal - tried docking station, and another external HDD case - no effect, same as above. No clicking noise, no lights, no signs of life.

At this point I took off both PCBs(took a long time: no torx, but I was determined), to see if there are any visible and obvious signs of my stupidity anywhere on the boards, but unfortunately it could not be seen with naked eye. Markings on the board are poor to non-existent. I could use some direction on what components i need to check and what else i need to do before i plug in the HDD into the (proper) PS long enough to get the data off of it. Any advice will be greatly appreciated.

Here are the pics:
PCB from WD HDD(110 0A90379 01), which seems to have been made by hitachi? In either case, I was NOT able to find that exact same board online anywhere. Either revision or something else was always different. I measured the bottom left diodes(hopefully) that appear to be shorted. Third larger 'presumably' diode gives 1.27 in one direction and .528 in another.
Attachment:
wd.JPG
wd.JPG [ 2.7 MiB | Viewed 395 times ]

Here's a picture of the same board that i found online. Not identical in markings, but components look the same (for better clarity)
Attachment:
diode.jpg
diode.jpg [ 317.35 KiB | Viewed 395 times ]


Here's the Seagate board (100721570 rev E):
I was able to find that exact(allegedly) board online. I will have to find a local soldering guru to transfer the bios chip, but aside from that I would still like to attempt to see if I could rectify the problem singlehandedly. Far left diode appears to be shorted.

Attachment:
seagate.JPG
seagate.JPG [ 2.28 MiB | Viewed 395 times ]

better quality pic found online:
Attachment:
PCBs-l1600.jpg
PCBs-l1600.jpg [ 241.66 KiB | Viewed 395 times ]


Any advice or insights would be hugely appreciated.


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 Post subject: Re: External HDDs - wrong power supply, need advice.
PostPosted: September 5th, 2019, 16:32 
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Joined: September 8th, 2009, 18:21
Posts: 11714
Location: Australia
The damage in both cases has probably been restricted to the 12V TVS diode, fuse, and zero-ohm resistors. Snip the diodes, and flow a blob of solder over the fuse and resistors.

Heed the warnings in my FAQ.

TVS Diode FAQ:
http://www.hddoracle.com/viewtopic.php?f=100&t=86


Attachments:
12V_TVS.jpg
12V_TVS.jpg [ 100.11 KiB | Viewed 368 times ]
TVS_diodes_fuses.jpg
TVS_diodes_fuses.jpg [ 103.9 KiB | Viewed 368 times ]

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 Post subject: Re: External HDDs - wrong power supply, need advice.
PostPosted: September 5th, 2019, 18:36 
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Joined: September 5th, 2019, 12:42
Posts: 5
Location: Canada
You, Sir, are a savior and my hero! I just messed around with the seagate drive, 0 ohm resistors seemed to measure ok, so I clipped the 12v diode that you pointed out and bam! The drive came alive! Said it needed formatting, but after i put it in the original external cover - i was able to access it. Copying it over now! In my panic, I've already ordered new PCB for it...gonna staple it to my desk as a diligence check. Thank you, very much!!

As for the second PCB that came from the WD drive. I have a couple of questions: the diode looking box on the left side of the 12V tvs - i assumed it's a diode...is it relevant? It seems to measure as a short. There is another identical component at the very top - center of the board, which seems to measure appropriately for a diode (open& .204)
12V TVS diode does appear to measure as a short as well. But the 5V measures 1.260 one way and .523 the other way on a diode check. Are those values acceptable for that PCB or the component needs to be cut? I just find it weird to see different values across something that's suspected to be a short. I'd like to clarify those things before I demolish more diodes, especially since I was not able to find an identical PCB, anywhere. The fuses are potentially ok, i did see a short on both of those locations, though I had to play with the multimeter a bit.
I appreciate your help in this.


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 Post subject: Re: External HDDs - wrong power supply, need advice.
PostPosted: September 5th, 2019, 19:13 
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Joined: September 8th, 2009, 18:21
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Location: Australia
The other diode to the left of the 12V TVS diode is a Schottky rectifier. I believe its function is to protect against reverse polarity. If you snip the 12V TVS diode, the short across the other diode will most probably go away. That's because the two diodes are connected in parallel.

The 5V TVS diode is OK. The other diode in the centre of the PCB is part of a switchmode power supply. Don't touch it.

The reason that the Seagate drive "needed formatting" is that the external enclosure is configured with a sector size of 4KB. When connected internally, the drive presents a sector size of 512 bytes, thereby rendering the data inaccessible.

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 Post subject: Re: External HDDs - wrong power supply, need advice.
PostPosted: September 5th, 2019, 22:14 
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Joined: September 5th, 2019, 12:42
Posts: 5
Location: Canada
You were absolutely right, as soon as I snipped the 12V TVS diode, the short did go away from its neighbour.
I very much appreciate your help, everything I was able to do today was thanks to researching your 5yr old posts on WDforums and also to your sound advice here. I could not find any specific descriptions of either PCBs anywhere online, so your positive identification of components was priceless, particularly with the WD board, where I was at a complete loss. Hats off to you!


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 Post subject: Re: External HDDs - wrong power supply, need advice.
PostPosted: September 6th, 2019, 11:11 
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Joined: January 8th, 2008, 5:21
Posts: 881
Location: uk
Quote:
I've already ordered new PCB for it...


Slow down and check first as many model drives have unique info stored in memory on the pcb which means you can't usually just swap it out.

Might be better to replace the tvs diode???


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 Post subject: Re: External HDDs - wrong power supply, need advice.
PostPosted: September 6th, 2019, 16:09 
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Joined: September 5th, 2019, 12:42
Posts: 5
Location: Canada
I was able to find the exact same board with the correct revision for seagate, so I will attempt to replace the cut diode - it's an easier one to do anyways since it's on the edge. I couldn't find the correct board for the WD drive. I do want to ditch the SATA to USB connectors though, so after all data is transferred, I intend to plug the drives in directly and format them when prompted. If that's not the best way to get this done - please let me know.


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 Post subject: Re: External HDDs - wrong power supply, need advice.
PostPosted: September 6th, 2019, 16:38 
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Joined: September 8th, 2009, 18:21
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Location: Australia
You can buy a replacement diode for $1. Something like an SMBJ12A will do.

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 Post subject: Re: External HDDs - wrong power supply, need advice.
PostPosted: September 8th, 2019, 20:34 
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Joined: September 5th, 2019, 12:42
Posts: 5
Location: Canada
Thanks for the info, I'll order the diodes. And thanks again for saving the day!!


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