Help locating electronic component

Hi,
The PCB on my Hard drive had a short circuit (probably because my brother connected 2 power sources to the drive)
Now its motor wont spin.
Would like help locating electronic component that blow up on my hard drive PCB,
I got the exact same hard drive from eBay - replaced the PCB but the drive is not working.
I would like to get the damaged electronic component (WE 75A) if you could help me locate it - I will appreciate it.
I prefer not to extract this component from the new drive because i don't want to ruin its PCB.
If you think i need to replace more parts - please share your thoughts.
Thank you for your help.

Damaged :
http://imageshack.us/scaled/thumb/824/img9472f.jpg

The new drive:
http://imageshack.us/scaled/thumb/38/img9473zb.jpg
12 answers Last reply
More about help locating electronic component
  1. The damaged component is a 5V TVS diode.

    See http://www.users.on.net/~fzabkar/HDD/TVS_diode_FAQ.html

    ISTM that your drive may be a Hitachi. If so, then you cannot simply swap PCBs. In fact in some cases you may also cause your donor PCB to stop working on its own drive. You need to transfer an 8-pin NVRAM chip from patient to donor. If you can provide a full photo, then I will be able to identify the NVRAM for you.
  2. Wow thanks for the article,
    So should I go ahead and try change the just the NVRAM from the bad PCB (patient) to the good PCB (donor)?
    I think this is something I am capable of doing...

    here is the picture of the PCB:


    I now recall asking you this once..
  3. The NVRAM is located at U5, at the bottom right corner of the PCB, to the left of the screw hole.

    If you are not adept at soldering, your local TV/AV repair shop should be able to transfer the chip for you.

    Onepcbsolution.com also offer a firmware transfer service for US$20 if you have purchased your board from a different supplier:

    http://onepcbsolution.com/firmware-xfer-without-pcb.html
  4. Hi fzabkar
    This is indeed a Hitachi drive,
    It even states that its prohibited to connect both power terminals, what a poor design... :??:
    Anyway
    Here is a comparison of the new and old drive (old on right) and the NVRAM's
    Do you still think its a go to replace the NVRAM?
    Thank you very much for your help!

    http://i.imgur.com/McWSG.jpg?1
  5. Hi Fzabkar
    According to the guide there, the donor is ok, I replaced the NVRAM.

    I connected the hard drive to the PC - but it motor won't spin.
    In windows Disk management console I can see additional disk with the correct size (marked as uninitialized)

    I double checked the NVRAM connections using multitester.
    I also connected the drive to different sata and to regular power (old style)
    But it won’t spin.

    One more test I did:
    I reattached the PCB (with the old NVRAM) to the working hard drive (so its the new PCB and new HDD with old NVRAM)
    -the new HDD won’t spin either.


    Any other Idea?
    Thank you for your help.

    Here is the NVRAM on top of the existing legs after soldering:

  6. You installed the chip backwards :-(
    http://www.users.on.net/~fzabkar/HDD/Hds722580vlat20_nvram.jpg

    The dimple in the plastic package should line up with the white dot on the PCB. That's pin #1.

    http://datasheet.sii-ic.com/en/serial_eeprom/S93C76A_E.pdf
  7. WOW I am so Dumb,
    I hope i didn't damage it
    I will rotate it and post the results

    Thank you!
  8. I'd be very surprised if the chip survived.

    All may not be lost, however. In some drives the contents of the chip are backed up in a firmware module in the hidden System Area on the platters. Whenever possible, the following PCB supplier offers a free "PCB adaptation service":

    http://www.donordrives.com/services

    However, you might like to keep the following thread in mind:
    http://www.tomshardware.com/forum/294386-32-controller-board-replacement-again

    Before sending off your drive, I would ask if your model's NVRAM can be recovered in this way.
  9. fzabkar,
    The NVRAM was rotated on the new PCB (Donor PCB with patient NVRAM) patient HDD still wont spin.
    If I assemble the same PCB (Donor PCB with patient NVRAM) on the Donor HDD - it will now spin.

    Do you think the motor is burned patient HDD after the TVS diode exploded?
    Can i replace the motors without opening the drive?

    Thank you for your help!
  10. The spindle motor receives power from the +12V supply, so I think it is unlikely that the motor is damaged. In any case you can measure the resistances between each pair of motor terminals and compare them against the donor.

    The +5V supply powers the motor controller's digital logic, plus the preamp inside the HDA. If the preamp is damaged, then your DIY adventure will be over. Some drives won't spin up if the MCU cannot detect the preamp. I don't know if yours is one of these but you could test your donor HDD by placing a business card between the PCB and the HDA connector. If the drive now doesn't spin up, then this will prove that the MCU needs to see the preamp.

    Another possibility is that the patient's preamp is shorting the -5V supply. If the patient drive spins up with the business card, then this would tend to confirm a shorted preamp.

    BTW, I am amazed that the NVRAM appears to have survived.
  11. fzabkar said:
    The NVRAM is located at U5, at the bottom right corner of the PCB, to the left of the screw hole.

    If you are not adept at soldering, your local TV/AV repair shop should be able to transfer the chip for you.

    Onepcbsolution.com also offer a firmware transfer service for US$20 if you have purchased your board from a different supplier:

    http://onepcbsolution.com/firmware-xfer-without-pcb.html



    Thanks guys I saved the HDD from my neighbour by swapping NVRAM of a donor HITACHI. It really works!
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