Seagate 320GB ST3320820A - PCB swap?

[SeagateTrouble]

Can anyone help me?
My wife fried my Seagate External HDD by connecting a laptop power adaptor by mistake.
The USB->PATA interface circuit in the external case seems ok... but the drive itself creates a short of some kind, meaning the indicator light on the power adaptor and on the interface circuit flashes on and off when the actual HDD is connected up. With the HDD removed (i.e. just the external case and the interface circuit, the power light is on continuously). Tried powering the actual HDD from a PC tower's internal power supply - the entire PC tower fails to power up...
All this means I suspect either the HDD's own PCB is fried, or worse still, something bad's happened within the HDD's sealed components (e.g. motor, heads).

Would like to try swapping PCB for a new (working) one... details as follows:

Seagate Barracuda 7200.10 Ultra-ATA
S/N 9QF0BC89
ST3320820A
P/N 9BJ03G-560
Firmware 3.AFE
Date Code: 07154
Site Code: TK

Can anyone sell me an identical unit so I can try the PCB swap? There are some valuable photos I want to recover.

Thanks

[pcimage]

Hi

Post a pic of the PCB so we can locate the TVS for you.

If you feel you're not up to the job, I'm in Peterborough and can sort it out for a nominal charge.

Cheers

Sean

[SeagateTrouble]

Thanks to all for speedy responses.
Will check out other posts regarding TVS but for now please see attached a pic of the PCB in question. Let me know if you need further info e.g. full details of what's printed on the chips etc.
Would welcome any further advice or suggestions.

Thanks

Attachments

Seagate PCB

SeagatePCB.JPG (46.01 KiB) Viewed 35798 times

[pcimage]

Check the two black components bottom left, one going up/down, the other left/right.

Check them for continuity, they should NOT be shorted.

[SeagateTrouble]

Having looked at some other TVS posts now, I'm getting a better idea of what might be wrong. Thanks again for amazingly speedy advice!
A potentially dumb question now arises - apologies if so - but:
Will the difference between normal continuity and a short be obvious for these TVS components? I'll be relying on an ex-broadcast engineer mate for multimeter skills, but for now just dredging up my own v. rusty knowledge of electronics, anything below ~100ohms is often treated by multimeter as equivalent to short is it not?

[SeagateTrouble]

Sorry Spildit I didn't notice your latest post while asking my (possibly dumb) question on multimeters. Thanks to you and pcimage for the advice. I'll assume 'diode mode' will make all the difference in being able to determine what's up (I'm sure my qualified mate will be fine with it all anyway!).

[SeagateTrouble]

Thank you once again for such speedy and detailed advice.
What you've said all makes perfect sense.
Having googled Transient Voltage Suppression Diode I'm beginning to appreciate what these things do. I'm thankful such things exist on these PCBs!

Sorry to drag this out...some more questions arise (prior to me getting assistance from my multimeter mate) - with apologies if any of these repeat other posts elsewhere on forum:
1) Assuming fault is found with one or both TVSs, what's the recommended procedure for removing it/them?
2) How big a risk am I taking powering the HDD up if I've removed one or both TVSs?
3) Regarding choice of (temporary) power source - assuming faulty TVS has been identified and removed - I was considering connecting the HDD back up to its original power supply in the external enclosure since this seems on the face of it to still be functional. Would I be best off avoiding this and using PC Tower instead, or is there a way of verifying the original power supply - perhaps with a multimeter? - checking for 5V and 12V at the correct amperage at the relevant points? It's more convenient for me to use the original supply if possible since PC Tower is not my own.
4) Is it generally a fairly straightfoward task to source a replacement TVS component and install it on the PCB?

Once again all advice gratefully received.

[SeagateTrouble]

Sorry - just answering my own question (2) from re-reading one of your earlier responses

But remember that the protection will be gone and you will need to replace them for safety if you want to re-use the drive.

Understood, but just need to know what kind of external surges are likely to occur while I'm attempting to copy off data. Is there a minimum-risk approach to powering up the HDD with TVSs removed?

[pcimage]

Assuming your PSU or USB caddy is know to be good, then you should be OK.

Go for it, and good luck!

[BlackST]

How to put data at risk... Chapter one...

[SeagateTrouble]

Ok, thanks for the advice.
I was just wondering whether TVSs are there on HDDs as a result of general unreliablility of power supplies - in other words, I wondered if the expected tolerances encountered on 12V/5V power lines in these environments through normal usage was something that required TVSs to be present?

But from what you say, it suggests they're really there to guard against the extreme and hopefully very infrequent cases where significant spikes or surges occur due to unusual events - and as a result, removing a TVS and running up the HDD for as long as it takes to copy off the data is a risk worth taking? Maybe a bit like entrusting your life to a qualified skydiving instructor on a tandem jump?

I may be being ultra-paranoid and I suspect I'm going to go for it anyway, but thought I'd ask the question.

Thanks to all for such helpful advice. This really has been one of the most useful forums I've visited.

[SeagateTrouble]

Thanks again Spildit. Appreciate what you're saying. I think you and others here have armed me with a lot of really handy info and I'm very very grateful. Time to take some action and hopefully get my data. I'll post the result here once I've done it... fingers crossed!

[SeagateTrouble]

Ok, well, here's an update...

I got a multimeter and identified the shorted TVS - it seemed to be just one of them giving a '0' reading in both directions. I'm pretty sure it was the one on the 12V line (based on it's location near to that side of the power input connector).
The other one was giving a "1" in one direction and something like "485" in the other.

I used some mini cutters to snip out the shorted TVS from the PCB.

Then out of curiosity I turned the multimeter to measure DC Volts, turned on the original external enclosure power supply and measured the volts across each of the pins in the power connector (the one that was originally plugged into the Seagate HDD. The readings were a steady 12V and 5V across the relevant pins.

Then I salvaged an old Fujitsu 7Gb HDD off my very old tower PC, plugged it up to the external enclosure power connector, attached an IDE->USB convertor cable, and switched on the power.... the old HDD then spun up with no problems and when I plugged the USB cable into my laptop, it came up fine and I could read the data on the drive.

Hurrah I thought - my external power supply is good, at least. Now to try the same thing with my troublesome Seagate with the shorted TVS removed.....

So I followed the same steps with the Seagate....turned on the power and......NOTHING. No noise of motor spinning up, nothing. Just seemed to be dead. Rather than try anything else I switched off the power after what must have been about 5 seconds. Didn't get as far as plugging the USB end of the IDE->USB cable into the laptop.

I was expecting some motor noise at least - since that's what used to happen with the Seagate before it got fried.

Spildit, anyone.... is there anything else I can try or am I doomed to have to send this in for professional data recovery now? Was wondering if a PCB swap (from an identical unit) might be worth a shot?

Thanks.

[SeagateTrouble]

Incidentally, when I did connect up the Seagate to the enclosure power, the indicator light was continuous...so I'm guessing I removed the correct TVS.

I know you advised me to use the tower PC power supply, but I figured it must be ok if the Fujitsu was happily running off it.

Note that in all of these tests I only used the power supply from the enclosure - I steered clear of the PATA/USB interface bit.

[pcimage]

If you've removed the TVS(s) and it still doesn't work, then you may be at the end of what you can do yourself, without potentially buggering it up completely. You may get lucky with a new PCB, or two, or three.

At this stage, pro DR won't be as expensive as you think, maybe £100-£150 tops. PM me if interested.

[SeagateTrouble]

I've checked again with the multimeter - there's no short across the power input connector pairs now - both the 12V and the 5V pairs read "1" in one direction and "438" (5V line) and "832" (12V line) in the other direction. These same readings are given directly across the remaining TVS, and the place where the shorted one used to be.

Looking at the PCB I can see another component that looks like it might be a TVS near where the orange motor lines emerge from beneath the board. If you look at my original photo earlier on in this discussion, it's just below the "C" on the white sticky label, in the top right hand corner. I've measured this though and it gives readings in both directions so I assume it's not the same thing!

Right, well, I guess I'll have to try a PCB swap.
Any advice welcome on where on the web to look for it.

[SeagateTrouble]

pcimage - I'll bear your offer in mind if it comes to it. Thanks.

[kenmackow]

THANKS ALL! After finding this forum, I tried your instructions on my FULL Seagate Barracuda 7200.11 1 terabyte drive. I did the same dumb thing and used a laptop power adapter by mistake. The first post on this page is almost identical to my problem, EXCEPT, I was the one that did it, not my wife. After testing the TVS, I found 1 burned out. I removed it and VOILA, the drive works like a charm. I am going to replace this Seagate with a Western Digital though. After searching for my answer, I found out this drive is prone to locking up or crashing. Now I'm scared. I backed up (which I DIDN'T do before) my 1 terabyte of movies onto 4 250 gig WD drives. I'm gonna get a WD 2 TB AV-GP Green Power hard drive to replace this Barracuda in my home theater. Again, thank you for all the help.

[N.C.]

WD?....
Khmmm...

[kenmackow]

Why not Western Digital? Who's left. Seagate owns Maxtor.