WD 640 Caviar Blue PCB Swap??

[kadoendra]

Hi,

I have an external WD elements of 640 GB in which i accidently put the power supply of my laptop. Since then my drive is dead. I openend the case and inside is a Wd6400AAKS hard disk.

The PCB number on the white sticker says: 2061-701590-L00 01P XC 7G04 0482 N 0003110 9113. The DCM is: HGRNHT2MGB. The board does not have a U12 chip.

I have another external harddisk which still works. This is a WD 500GB Caviar Green. Altough I know better i thought i give it a shot and swapped this pcb with the other one. I almost was very happy because the disk now spinned and Windows recognized a USB hard drive and even that it was a WD. However it didn't show up in the explorer and in disk manager i cannot get it initialised.

SO my questions are the following:

- in similar threads i've read that changing the PCB with one that is (almost) exactly the same with the defect one is no guarantee to succes. And since my board doesn't have a U12 chip I have to get someone who is capable of doing a firmware transfer. Is this still valid in my case? Is the fact that my drive almost was accessible in windows with a pcb from a totally different drive (500GB vs 640GB) a sign that swapping with a more exact pcb will possibly work?

- if not: will the trick with live pcb swapping where you put a working drive to sleep and swap the pcb on your working drive to the non working drive and then wake up the drive work? This is the trick i am talking about: Whitepapers | My Hard Drive Died! | Scott A. Moulton

I hope somebody can answer this questions. Apologies for possible grammar mistakes. English is not my native language.

Kadoendra

[labtech]

Indeed every WD PCB has unique parameters. To get your drive to work have to get another compatible PCB and then use special software to adapt the new PCB to your drive. The software is not something available to the average person. So you may want to look into data recovery service.

[dmarques]

yes, even to make an hotswap you need some knowledge to know how that can help to reach your data.
If your data is valuable it's better to take it to a pro. if not, you can mess with it.

[fzabkar]

The problem is most likely a shorted 12V TVS diode. You don't need a "pro" to fix this. If you are lucky, a DIY repair will cost you nothing.

Just remove D4 with flush cutters, and then check whether R64 is open. You may need to invest US$10 in a cheap digital multimeter.

Upload a detailed photo of your board for more detailed information.

[kadoendra]

Thanks for the reply's. Here is a picture of my board: http://img155.imageshack.us/i/0002small.jpg/

[fzabkar]

I can't see any visible signs of damage. However, D4 and R64 are the most likely culprits. Set your multimeter on the 200 ohms range and measure the resistances of both components. Also measure D3 and R67.

R64 and R67 should measure close to 0 ohms. If either is open, then bridge it with a wire link or blob of solder. If either D4 or D3 measures close to 0 ohms, then it is shorted, in which case cut it out with flush cutters. The drive will work OK without it, but it will no longer have overvoltage protection on the affected supply. Be absolutely sure your PSU is OK.

If, for continued protection, you wish to replace the diode, then a 5V TVS diode can be substituted with an SMAJ5.0A, and a 12V diode with an SMBJ12A. They can be ordered from Farnell, Mouser, Digikey.

[kadoendra]

Thanks alot. I myself am not so familiar with measuring resistance et cetera with a multimeter but I will ask some friends if they can work with tour explanation. One minor question: what does PSU stand for?

[fzabkar]

PSU = Power Supply Unit