This is Chapter Two of my epic saga continued from: http://forum.hddguru.com/hdd-1tb-logic-board-fried-t11672.html.

Our new patient is a Seagate 750 GB Barracuda 7200.10.

ST3750640A
P/N: 9BJ048-305
Firmware: 3.AAE
Date Code: 07147
Site Code: AMK

The barcode on the logic board says 100406537 C 7711R21V, and the image is attached (?). The magic smoke came from one of the square black thingies (Zener diodes?) in the upper right near the power connector.

I bought a donor logic board off ebay with the following info:

ST3750640A
P/N: 9BJ048-305
FM: 3.AAE
Site Code: WU

And the barcode says 100406534 G 78098QKU, image also attached.

So everything's at least really close, right? Well, I installed the board and plugged in the drive. The drive spun up, and there was one click, and the bios took a lot longer than normal to... not detect the drive.

I actually have two of the same drive that died, so it would be really awesome to figure this out. Can I replace the diodes? Would they have fried anything else? I at least have some known good donor parts. Can I swap the firmware chip(s?) like you supposedly can with the WD? Can anyone recommend test points for diagnosing exactly what died?

Thank you everyone for your help. The thought of losing all my movies and TV just makes me a bit numb.

ps. Sorry the scanner makes things blurry. I can take more detailed photos if it would help anyone.

So per the advice of a PM (thanks), I removed the blown diode (TVS) and plugged the drive back in with the old board. At least no more magic smoke, but the result was even more disappointing.

First the drive spun up. So far so good. And then click-bounce-bounce-bounce as what I guess was the heads being driven into the stop at full speed and bouncing. Awesome. Then after a few seconds, a repeating pattern like:

Beep... chicka-clunk.
Beep... chicka-clunk.

I think that's the sound of an "unfortunate turn of events." Probably the VCU or something is fragged as well? Can I swap just the firmware bits? Thanks for all your advices so far via PM. I won't quote private messages unless I know why they were private, for your privacy.

No, at this point you have some mechanical failure.

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You don't have to backup all of your files, just the ones you want to keep.

TVS is there for a reason.

I usualy test a board without a drive itself to make sure there is no other shorts, which could damage Preamp or a motor.

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www.datarecoveryne.com

Your power supply most likely ruined the preamp. Don't let the drive click. Contact a professional if the data is valuable.

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Buy your friends Toshiba\Hitachi and your enemies Seagate.

Well, I had a pretty good day today. Except for anything computer related.

So I have a twin of that drive that was smoked at the same time, and it looks like the same TVS is fried. Any other suggestions besides "contact a professional"? Which is of course a reasonable and logical suggestion, it's just that I don't have $600 x 4 to spare. Are there bulk rates?

Would the pre-amps in both drives have blown at the same time? I do have access to a cleanroom and nice EE equipment, and while I haven't previously done a successful head swap before, there's always a first time.

Don't make your first time on a drive with data you care about.

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You don't have to backup all of your files, just the ones you want to keep.

I'm afraid to see Chapter Three of the Epic Saga...The Saga sank taking all hands down to the bottom...

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Buy your friends Toshiba\Hitachi and your enemies Seagate.

Here we say 'one hand in front and one behind' (note: close to the body and below the waist). Have a good day.