I have a few Western Digital WD1001FALS 1 TB hard drives and they have been pretty reliable for the past few years until recently. One of my WD1001FALS’ died suddenly a few months ago. Since it was still under warranty, I sent the dead drive back to WDC and swapped for a replacement drive. A couple of weeks later however, another drive failed in a similar manner (the harddrive would not spin up). Instead of sending it back for another RMA, I decided to take a better look at what was causing the failure and see whether I could fix the drive myself.

Unlike a typical harddrive failure mode, in which you can hear the clicking noise from the drive heads trying to locate the tracks underneath, these drives simply stopped spinning. My suspicion is that the motor controller and/or possibly some other components have failed for some unknown reason. Initially I suspected that the power supply might be at fault, but after some repeated testing it seemed that all the voltages/ripples were well within specifications. Plus, I have two other hard drives in the same computer and neither of those drives were affected. So I began to think that it might have just been some unknown transient events that somehow only affected the two Western Digital drives specifically.

I pulled the dead drive out from the PC and unmounted the PCB. At first it appeared that everything looked normal (see picture below). The +12V and +5V pins on the SATA connector does not appear to have been shorted to the ground (there are protection TVS diodes on the power rails, in an over voltage event they are likely to be the first ones damaged. This usually manifests as a shorted power rail). But after some careful examination, the spindle motor driver chip marked as SMOOTH L2751 3.1 seemed to have suffered some thermal damage.


There was a tiny burned mark towards the lower right of the chip. It didn’t show up well in this picture, but you can see the damage clearly in the picture taken below after the chip was removed.

Controller Chip Damage Close-up
Controller Chip Damage Close-up

With no other signs of physical damage, I decided to take my chance by swapping out the spindle controller chip. Unfortunately there is not much information on the Internet about this particular chip, which is not surprising as these controller chips are aimed at highly specialized markets and are not designed for the typical consumers. The closest match I could find any information on is for ST’s L7250, presumably L7250 and L7251 are very closely related in terms of design and performance.

Sourcing L7251 V3.1 turned out to be another challenge. I could not find this chip anywhere in the US from any of the major component distributors. Eventually I ordered a couple from Aliexpress. After a few of weeks’ waiting, my order eventually arrived and the chips looked to be identical to the failed controller chip pictured earlier, the only differences appeared to be on the date codes and serial numbers.

New Controller Chip
New Controller Chip

Encouraged, I soldered the replacement chip onto the controller board using my hot air rework station. And to my great surprise the replacement chip actually worked right off the bat! The harddrive came back to life after I mounted the circuit board back on. Better yet, everything on the harddrive remains intact! To be honest, I didn’t expect it to be this easy (in general Murphy always wins).

Of course, I might have just been lucked out since the damage was apparently isolated within the spindle controller chip. Had there been an issue with the microcontroller chip, chances are that I wouldn’t be able to get the harddrive back in working condition again even if I were able to swap out the motor driver chip. This is because like most modern harddrives, WD1001FALS stores its calibration information within the MCU itself instead of on a separate EEPROM and that information varies from drive to drive. Without the calibration information, your chance of getting a working drive is pretty slim.

As to why the drive failed at the first place, I will probably never find out the true reason. It might have just been some totally random events, or it might have been some potential design flaws. Anyway, I did manage to fix the drive and now I have an extra L7251 V3.1 to spare, let me know in case you have a drive failed the same way and you wanted to give it a shot and try your luck…

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8 Thoughts on “Bring a Dead WD1001FALS Back to Life”

  • well well… what a surprise!
    I also have a WD1001FALS (Caviar Black) and it stopped working.
    After reading your very helpful article, I checked the chip and it has the same burn, slightly more to the center.
    It actually has burned the foam cushion over it, as well. I have heard many similar stories with these HDDs.
    To me this sounds like a design (chip) flaw.
    I am a tinkerer, but don’t have a hot air soldering station.
    Anyway thanks for the information, and if you ever need anybody for a “class action law suit”, I’m available :-)

    • Very interesting. But it may just be that these drives’ are more susceptible to voltage spikes or things of that matter compared to other drives. Whenever this kind of failure occurs, there are many different factors at play. For instance, it could also be issues with power supply… Given that they all have 5 years warranty and WD’s customer service is very good in general, I wouldn’t jump into any conclusions too quickly.

      Hopefully you had backups and did not loose any important stuff.

  • Hi Kerry and thanks for the swift reply.
    First and foremost, I have not lost a single byte. I’m a backup hoarder. All my data is on multiple external backups 4fold :-)
    The “lawsuit” comment was meant as a joke.
    One question that comes to mind is that my HD is an Apple branded one. It came with my Mac Pro just over 2 years ago. Does WD cover these disks with the same 5 year warranty? I ask mostly out of curiosity because I just ordered the chip and will attempt to repair it (I bought a cheap hot air soldering station as well, but don’t tell anybody).
    Again, thanks for this very enlightening conversation.

    • Yeah, I back up my files religiously as well. If I recall correctly, WD only handles the RMA process for retail drives (both boxed and bare), but not from the OEMs.

  • thanks for your post i have the same problem
    do you change only the smooth chip ?
    i mean you dont need to change anything else like reprogram something?
    i ll buy chip and post what happend

    • Yes, I only changed the SMOOTH chip. For WD1001FALS the firmware data is stored in an on-board EEPROM, so depending on what exactly caused the failure (assuming other part of the circuitry is not damaged) you only need to change the chip itself.

  • Dear friend,
    I have a Western Digital WD20EARX, used as an external disk with sata to usb adapter. Adapter’s PSU failed caused power protection circuit on HD burn (some kind of diode Zener ).
    Took out burnt diode (zener) make disk run again, but seems that data are not in order, using some kind of software to restore data i can see files but when i restore them zero bytes lenght.
    Have you ever had any simiral issue? i can provide more info.

    Have a nice day

  • WOW! I am super impressed. Your soldering skills must be off the chart.

    I am having a very similar issue.

    Basically when I book up my machine I get the error message “ the disk you inserted was not readable by this computer”

    Though Unmounted, in disk utility the drive come up in the left side of the window named “Media” but shows no files and a capacity of Zero KB.

    I tried running first aid, but nothing happens.

    So the computer can see there is a drive but cannot see the files or any storage space.

    Of course… I don’t have it backed up and am now really worried I have lost all my data for good. Really not up for paying hundreds to go to a data recovery service either).

    I would love to know if you have any suggestions Kerry.

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