WD1001FALS power failure - diode replacement?


My 1TB WD1001FALS suddely stopped spinning up (unfortunately, this happens to be my backup drive, and I don’t have a backup of my backup).  I tried connecting to a different SATA port on my motherboard, used a different power supply connector, and also tried an external enclosure - I get no activity from the drive at all (can’t even feel any vibration).  I did notice that the SMOOTH L7251 2.2 motor controller was getting rather hot (although there are no burn marks).  Also, around the time this happened, I was adding some other drives to my PC, and at one point the poer supply only turned on for a split second before shutting down.  Once I removed the drive, everything powered up OK.

I removed the PCB and checked out the TVS diodes D3 and D4 with an ohmeter set to 2K range.  D3 measured 405 Ohms, D4 measured 656 ohms.

I also checked Schottky diodes D1 and D2.  D1 measured 1 ohm, and D2 was 138 ohms.

I assume from these measurements that D1 needs to be replaced.  I see a marking of “BCG.”, which leads to me the following datasheet (based on fzabkar’s excellent post)


I wanted to check with someone more knowledgable before I actually start soldering on the PCB (or have someone else do it for me :slight_smile: ).  Am I on the right track?  If so, what part should I get?  The diode datasheet has 4 different part numbers for this device code.

If it helps, the part number of the PCB is 2061-701567-400 AF.

Let me know if I need to post any other details, and thanks in advance for any help.

Hi there and welcome to the WD community.

I have not tried this, lets see if another user can help you with the information you require and some tips on this matter.