Cutting a long story short, I managed to briefly connect my HD power (via molex) the wrong way around. This means I supplied 12V to the 5V rail and 5V to the 12V rail. This brief connection made my PSU shut down and shortly after I could smell the dreaded smell of burnt electronics.

Presumably, my data is fine and something blew on the HD PCB. Sadly, I'm at university and don't have access to my tools (most importantly, a torx screwdriver set). Before I go out and buy some torx bits, what are the chances I've just blown a TVS diode and the rest of the components are OK? I definitely can't afford the recovery, but there is some data on the disk I would be very upset to lose!

Any help greatly appreciated. Thanks!

Hi, I would say 50/50.
If not contact Sean @ PcImage he's in Peterborough, he will be able to help you out.

Regards/ Bosse

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You're not the first person to do that, and you won't be the last Despite being polarised, the soft plastic on the plugs means that with a bit of pressure, they will sometimes distort and go into the socket far enough to make contact when they're the wrong way round, as you have found


So if that drive's PCB has a working 5V TVS fitted, then the 12V would certainly have caused it to conduct - hopefully it did so quickly enough to prevent a catastrophic EOS event for other components. However, there has been at least one photo on this board recently, of a WD PCB on a reportedly new drive, without either TVS populated on the PCB Let's hope your PCB does have TVS fitted!


Don't forget you'll also need a multimeter (not all TVS damage is obvious visually) and ideally an ESD shielding bag (for the drive), ESD mat, and wriststrap etc., unless you want to risk potentially causing further latent damage.

A couple of thoughts: At your Uni, do they have an electronics lab and tools / multimeter / ESD bench which you could get temporary access to? That would save you some money on buying duplicates of tools which you already have elsewhere If you do need to buy tools / meter / ESD mat etc., then you could see if there is a Maplins store near to where you are (or you can order online). They often have Torx sets on sale.

As mr_spokk said, you also have options for getting professional help if this needs a major repair.

Good luck

I have a WD5000AAKS and opened it up for you. It does indeed have TVS's on board, D3 and D4. It's a SATA board though.

Good luck!

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I agree that we'd expect them to be there (from my limited WD experience - I expect you've got more than me ). But just because your board has the expected TVS fitted, does not confirm that the OP's board does

In this WD thread, the PCB (which that OP reports was not bought used, and where he reports that he hasn't removed anything) is missing the TVS at D3 and D4! The PCB pads are there, but no TVS... See what I mean?

logical-step-troubleshoot-wd5000-t18204.html#p121996

IMHO it's very strange (and perhaps there is another story there e.g. a repair before the drive got to that OP, where they forgot to fit replacement TVS?).

Hence why I didn't want to make the assumption that the expected TVS are present on silentwol's PCB, although I sincerely hope that they are there, and that the 5V TVS did its job!

Thanks for your help guys



Although I am fully to blame, I was actually using an eSATA backplate which came with my mobo, the design of which allows contact to be made both ways around, with minimal force. The pins/sockets simply aren't set back enough. Annoying, but I should know better. Hotplugging a drive containing the only copy files a bad idea.



The picture in the thread you linked to is indeed scary Fingers crossed I guess.



I do actually have access to a lab with the required tools.... I'd rather not bring non-course related work there, but I think it's probably my best option. I'll just say I have some very important project work stored on it (thankfully, all my truly important work is properly backed up!)

I'll take it up tomorrow and have a look. Judging by the smell of it when it happened, there probably will be some visible damage. Fingers crossed it'll be a TVS

OK, just got back from the lab. D3 was blown (measured as short circuit) and R67 was also blown (visible damage and measuring ~800Ohm). So, I removed D3 and short circuited R67 with a wire link. Have I done the right thing? I don't want to plug it in until I have an experts opinion!

Thanks

It will be better to replace D3 also for a future protection.

Good luck

Just tried it and the drive didn't spin up Any suggestions?

you need professional help. Try PCIMAGE, he will do you a good deal.

Unfortunately your drive stores unique, drive specific "adaptive" data within the Marvell MCU. These data need to be transferred to the donor PCB.

I believe your only DIY option is to attempt a repair, assuming that the MCU survived the overvoltage. If it turns out that a repair is not feasible, then the post mortem may be instructive in itself.

See this thread:
http://community.wdc.com/t5/Desktop/Har ... d-p/104584

If you can report back with the resistance measurements, then we can check the onboard supply voltages and narrow down the fault.

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A backup a day keeps DR away.

90% the MCU and/or Motor chip are damaged, repairing the entire PCB is almost not possible.

There's nothing you can do yourself but replacing the whole PCB. And sure you will need a pro help to transfer the adaptive data unique to each drive.

Good luck

Thanks for your help fzabkar!

I've just got home and I've taken another look at the drive. Here are a few measurements:
Resistance between Vio, Vcc and pin 1 of the RAM to GND: 1kOhm (http://www.users.on.net/~fzabkar/HDD/To ... in_reg.jpg). Seems a little low?

I then plugged in the power and measured Vio and Vcc and pin 1: 0.1V. So it seems the regulator is also broken.

Also, I measured R45 (as you suggested here: logical-step-troubleshoot-wd5000-t18204.html) and it's measures 80kOhm... not good?

The only visible damage was to R67 (now shorted) and D3 (now removed).

Any ideas on how to proceed?

Also, according to information here (http://community.wdc.com/t5/Desktop/Har ... d-p/104584), the -5V rail is measuring -0.1V. So that seems to be broken too. Not good!

silentwol,

It would appear that your motor controller combo IC is faulty. It controls each of the regulators.

Worse still, the fact that R45 is open would suggest that there is a problem with the load on the Vcore regulator. Unfortunately this means that the MCU is probably dead.

You can determine the resistance on the Vcore rail by measuring the resistance between ground and R45, at the end closest to the MCU.

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A backup a day keeps DR away.

Resistance from vcore to gnd is 90ohms. Does this mean the MCU is dead?

IIRC, others have measured similar Vcore loads on good boards, so the MCU may be OK.

One more check would be to measure the voltages on the capacitors near the SMOOTH chip. This would confirm whether +12V and +5V are getting to the IC.

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A backup a day keeps DR away.