Hello guys.. I had a small disaster today and was glad to find this forum.

The hard drive that died is:

Seagate ST3320620AS
P/N 9BJ14G - 305
Firmware 3.AAE
Date Code 07273
Site Code TK

Story
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It had been serving me for 2 yrs installed in an external esata enclosure.
I was worried with backing up my data because a few bad sectors appeared in one of the partitions so today I bought a new 1TB drive to take the place of the 320GB one in my external box. I planned to install the old one into the pc-case to transfer the files.

Therefore I connected both drives, powered up -> no sata drives detected.
The new drive just needed a jumper - as i have an old sata controller. But my old ST3320620AS is not spinning up at all.. Maybe my (old, too) PSU sent some weird voltage? Maybe it was some static electricity from the case? [I was stupid enough to leave it under the dvd drive without screwing]. I have no idea.

Result
------
Drive doesnt spin wherever i tried it in (ext enclosure - other pc).

There is no visible damage to the PCB.

As I learnt through searching, I checked the two TVS diodes on the upper left corner near power connector (green circles) with the multimeter and found them OK.

Now my question is: is this another TVS diode in the red cirle? This chip seems to be short'd both directions - 0 resistance. Visually I cannot see any damage, but it definately does not work as the two others. But is it a Transient Voltage Suppression diode or it is something else?


Any suggestions? I will try to upload some better pics tomorrow.

Attached follows close up of bottom left corner.

In better quality here:


Back of the pcb side:


Big front pcb pic:

I tried to add a reply with higher quality pics with live http links but my post is pending moderation.
Unfortunately I have kept the link only for one of them:
Lower left corner of the pcb:

http:/ / profile.imageshack.us/user/costheo/images/detail/#29/img7103c.jpg

hmm i found an auction for a pcb from a drive with similar details like mine, only site code is different, and has nothing soldered on the spot where there is the shorted chip in my pcb.

Picture here
http://i11.ebayimg.com/02/i/001/39/91/0d43_12.JPG
Auction
http://cgi.ebay.com/Barracuda-7200-10-S ... 2ea8023f97

I think I m going to try to cut or desolder that piece, and try my drive with the external enclosure again.

OK now at least i know that with 45$ I can have a possibly similar pcb to try..

The part does appear to be a (U)nidirectional TVS diode in the ST Microelectronics SMBJ 600W series, part number SMBJ13A-TR, marking code BUF:

http://www.datasheetarchive.com/pdf-dat ... 631289.pdf

The date code appears to be 626, ie 2006, week 26.

The working voltage is 13V as distinct from the 12V BUX TVS diode near the power connector.

Hi and thanks a lot for your reply!
After all I decided to move on removing the suspected TVS component but - no success. HDD still does not spin. Nothing gets warm on the pcb.

I m thinking that finding a combatible PCB will prove an easier solution, while keeping cost low.
Any advise for someone selling this pcb & shipping to Greece?

You have a pro in Greece from this forum. He can surely get your data back without hassle , without trial and error and avoiding getting uncertain PCBs etc. etc. Send PM to rafaela .

I can solve your problem too but in Italy as "next step" just in case, but first try in Greece.

I find it strange that a 13V 600W TVS diode failed but a 12V 600W TVS diode survived.

If you intend to swap the PCB, be prepared to swap the 8-pin EEPROM chip as well.

Are you sure there are no other shorts on your board? Are there any zero-ohm links near the power connector? If so, are they intact? Does the PSU power up?

There is nothing strange about it.
The TVS is not a power component in normal usage.
It is designed for protection.
The short-issue is only the malfuction wich fortunately helps to protect in some cases the other components.
If you don't understand the usage of the TVSes, read the datasheet of one.
In HDD of wich TVS gets shorted and wich not, only the PS and the fortune have influence...

Janos

I understand how TVS diodes work. The fact that a 13V TVS diode failed suggests that it was subjected to a sustained overvoltage, probably 14V or more. This same overvoltage should have destroyed a 12V TVS diode of the same power rating, but it did not. In fact, one would think that the 12V diode would have protected the 13V one. Of course I'm assuming that both diodes are sitting across the same rail. If not, then what is the function of the 13V diode?