Is the drive (WD1001FALS) repairable in this case?

Hi everyone,

Recently I installed a new PSU into my PC. It had modular cable connectors and I mistakenly tried to use SATA power cables from my old PSU with it. The cables had the same connector on PSU side but different pinout: +5V and +12V were swapped and it caused 2 hard disks to die. 

The Seagate drive prevented the PSU from starting because of possible short circuit inside, but the other WD drive did not although it was not spinning also.

I removed the PCB from my WD1001FALS drive. It had a burn damage on U1 chip (Smooth chip). I also tested the TVS diodes and one of them was dead (the one for +5V input). I removed this diode and tried to power it on in spite of burned controller. Certainly, it didn’t work.

I would like to know if the drive is repairable after all these things that I’ve done to it. For example can I get the U1 chip replaced or there are some other damaged components there for sure? And will the data still be readable after the repair?

Thanks in advance.

There is one user fzabkar he’s really good with the PCB, PM that guy is your expert.

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Depending on the model, the cure for the Seagate drive is to remove the 5V TVS diode and hope that it succeeded in protecting the rest of the electronics.

The WD drive unfortunately is a bigger problem. The SMOOTH chip is the motor controller. It generates the supply voltages for the Marvell MCU. Unless there is an 8-pin serial flash memory chip at location U12, then the “adaptive” data will be stored within the MCU, in which case a board swap will be difficult.

Transferring the SMOOTH chip requires an SMT rework station and considerable skill. Furthermore, if the SMOOTH chip is damaged on the side facing the MCU, then one or both of the MCU’s Vio and Vcore supplies may have sustained an overvoltage. Worse still, since the +5V rail also supplies the preamp inside the HDA, then this may be damaged also, in which case a head stack replacement would be required.

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replacing the head stack will require a clean room.  you’re looking at data recovery.

I already tried to do this with the Seagate drive. After I removed the TVS diode and powered it up I heard a crack sound and there were some smoke. One of the chips burned quite badly which can be seen even without removing the PCB (it turned brown from the back side). But it is not a big loss because the drive was only 160GB and had no important data.

But it is sad to hear about this kind of possible damage of the WD drive. Especially since it has no U12 chip. I’ll take it to a local hard drive repair place and hope for a lucky outcome.

The diode died because there was an overvoltage on the +5V supply. By removing the diode, you removed the short circuit. However, in doing so you also removed the overvoltage protection. ISTM that your power supply is still outputting an excessively high voltage. Therefore I suggest you measure the voltages with a multimeter.

I don’t think so because I used another PSU for this and it works good with my other hard drives now.

There is another thing I can’t understand: both drives had dead +5V TVS diodes. Before I removed them the PSU couldn’t start because of short circuit protection with Seagate drive connected. But with only WD drive connected it could start although I checked there was a short circuit between +5V and GND leads on the power connector in both directions.

It doesn’t make sense to me either, unless the zero-ohm resistor (R67) subsequently went open circuit.

I visited a repair shop today and the service man told me that this particular HDD model has the EEPROM data inside the drive case and not in any chip on PCB. So that I can swap the PCB and it should work if nothing is damaged inside. But from what I heard earlier the EEPROM is inside the controller on PCB. Anyway, they didn’t have a similar HDD so they couldn’t do anything. But what is the truth about EEPROM location? Does it make sense to look for similar PCB? My PCB is 2061-701622-800 02P. I can post a photo if necessary.

The only electronic component inside the “case” is a preamplifier. The EEPROM is on the PCB, either in a discrete flash memory IC at U12, or within the Marvell MCU. In your case U12 is probably vacant.

A straight board swap most probably won’t work, but AIUI you could be lucky (5% chance) if the tolerances of the “adaptives” are close enough.

FYI, here is what is inside your drive:

Here is the preamp on the head stack:

Here are several datasheets that may help your “service man” to understand the difference:

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Finally, I got this HDD repaired. After replacing the U1 chip, a diode and a resistor the drive works perfectly. The data is intact.


Please, can u tel me, where did you buy the U1 chip? I have the similar problem with WD1001FALS.

This U1 chip is burned.

Thx very much

Riseman wrote:

Finally, I got this HDD repaired. After replacing the U1 chip, a diode and a resistor the drive works perfectly. The data is intact.

Tell a chip Q1, the output voltage?

Q1 is an NPN pass transistor in a linear 3.3V regulator. Its collector (metal tab) should measure +5V. The base and emitter voltages should be +3.9V and +3.3V, respectively. The base is driven by the SMOOTH motor controller.


I bought the chip here. It seems they increased the price in two :slight_smile:

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