I’m trying to revive an old WD 18G drive well over 10 years old. It was zapped with a power supply surge. I swapped the fried board with a donor and now the drive actually spins up and is recognized in the bios. But when I boot into Windows XP OS, the drive is not recognized and then it makes a funny clicking noise. I’m pretty sure the next step is to lift the eeprom chip off of the fried board and switch it onto the donor board. My only problem is that the drive is so old, i can’t seem to find which chip is the eeprom. There are three possibles, all with 8 legs. Does anyone have any idea which is the eeprom? I’ve seen a lot of posts that indicate the U12 position on the newer WD drives is the eeprom. But my closest guess on my drive is the U7 position (I have no U12). Can anyone verify this? I really want to try this, even though my soldering skills will probably destroy the chip and render it useless. I’ve also heard that these drives were actually manufactured by IBM. Another possible problem would be the pre amp. Any help would be greatly appreciated. Thanks. PS, I had a primary IBM HD that also got zapped, and i was able to find an exact donor match, and the drive was revived with the pcb board swap only. No need to switch eeprom chips. Data recovered!
You can read the markings on all three chips, and then google them, to see which one(s) are eeprom/memory chips 
Does your drive have a squarish chip with a long part number beginning with “62-”?
If so, then this may be a 27C1024 parallel EPROM, in which case you will only need to match the 62- number (AFAIK). Later models have a serial flash memory chip.
A detailed photo might help.
Photo link below. Doesn’t show FULL SIZE on my IE browser. I resaved photo from IE and it was full size. So I’m not sure what’s up. Thanks!
Uploaded with ImageShack.us
U7 is a 93LC56 1K/2K/4K 2.5 Microwire Serial EEPROM:
http://www.selectronic.fr/includes_selectronic/pdf/Microchip/93LC56.PDF
That’s the chip you would need to transfer.
BTW, here is a direct link to the full-sized image:
http://img403.imageshack.us/img403/2577/wdac41800pcb.jpg
Yes, that’s the one (U7) we were thinking but had not received any confirmation upon our searches. This helps a lot. From what I’ve been told, the firmware on these drives is found both in the chip AND the preamp, and if they do not match, then NO DATA RECOVERY. There are still some very probable possibilities that the chip could be damaged during the desoldering and resoldering process, but hey, it is what it is. On that note – anybody have any technical advice regarding the actual chip removal process from the board? Once again, thanks for all of your help.
The preamp is inside the HDA. It doesn’t contain any firmware. However, I don’t know if it is matched to the board. If it is, then matching the DCM (Drive Configuration Matrix) on the label of the drive should account for it.
AFAIK, some IBM/Hitachi drives need to match both an EEPROM chip and a flash memory. The former contains “adaptive” data, while the latter contains a small amount of bootstrap related firmware. If your WD drive follows this approach, then I believe that if you match the MCU (the largest chip) or the drive’s firmware version, and transfer U7, then you should be able to retrieve your data. Be aware that swapping boards between Hitachi/IBM drives is dangerous because the MCU may rewrite the EEPROM data, rendering both patient and donor inoperative. This is not a concern with modern WD drives, but I have no idea whether there is any risk in your case.
Unfortunately I’m not a data recovery professional, so I suggest you take my advice with caution. However, at http://www.techsupportforum.com/hardware-support/hard-drive-support/ there is a DR guy named raptor-pa who should be able to provide you with an accurate DR strategy.
No news to report as of yet. Still sitting on donor PCB to make the chip swap. Just been too busy. It’s not a critical situation. I did check out techsupportforum and raptor suggested that the MCU chip swap would be necessary. I am still a little confused as my last question received no reply – which was basically, do I need to swap both, or just the MCU? I guess at this point, it’s up to me. I think my plan A approach is to swap eeprom first and if that still doesn’t get the drive recognized, try the MCU. Again, I’m not sure when I’ll have some time to work on this, but I definitely will report back and post my results. Hopefully soon!
