My PSU went out recently and it seems to have brought all my hard drives with it. All three will not spin up at all and all three of the PCBs have burns on chips labeled "smooth" on top, in addition to what appears to be a fried TVS diode here and there.

My main priority is to replace the PCB on my Seagate ST3500320AS (FW: SD04), but I also have a WD2000JS-00PDB0 which would be nice to get running as well.

From what little understanding I've gathered over the past few days, if I find a PCB for my Seagate which matches the HDD model number and I swap out the ROM/BIOS chip, then it may work? Say for example, if I bought this PCB and swapped out the 8-pin chip, I could be in business?

So, how silly does this sound? I have no sense of perspective. I could scrap together the money for this repair, but honestly some TLC with a soldering iron sounds a lot more fun. I think this because the repair doesn't seem beyond me, but I could just be missing something huge.

Any thoughts, comments, guidance, advice, etc. is greatly appreciated.

Hi,

Both model needs ROM transfer for repair.
And both model needs pcb PN matching.

Additionally, keep this on mind, the HDD have the preamp chip INSIDE wich can be damaged as well.
And some rare cases the damaged preamp chip can demagnetize the platters when the first pcb swap happens...
So if your data is really important, seek for professional help.
But if you decide to gamble with your data, the ROM swap will help you in both case...
Good luck.

Regards,
Janos

So, what exactly has to match on a replacement PCB (if the ROM chip is swapped). I can find boards with identical part numbers and revision numbers, but they appear to be by different manufacturers. The components have different numbers of them, such as the main chip (LSI). Usually there are some matching rows of numbers, but not all of them match (occasionally a row is completely different). Is this a problem?

Also, in playing around with one of my less-valuable dead drives, I put in a PCB with the same part number and revision number, but different firmware. If I don't plug the data cable in, the drive powers up and sounds fine. If I plug the data cable in, it makes a regular ticking noise. Is this a sign of a greater failure than just the PCB, or could this be a symptom of having the improper ROM chip installed?

As always, thank you so much
If any more info would help, please let me know. I really don't know what is important for you to know...

Swap the EEPROM chip. It stores drive specific calibration data determined at the factory.

See this article for an explanation why calibration is necessary:
http://hddscan.com/doc/HDD_Tracks_and_Zones.html

Identical chips can have different markings for several reasons. One is the date code, usually in YYWW or YWW format (Year/Week). Another is the batch code or manufacturing location. Some may even have a serial number.

If you have a specific example, perhaps one of the more knowledgable data recovery specialists can explain it to you.

Usually u need to match the board number.

pepe

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Adatmentés - Data recovery