Hello to all !

Please for help, yesterday i attach sata cable(computer is on ), then sata power cable, small part stj009 is blown, pcb is unscrewed, as you can see on the picture, 8pin mosfet is removed.

My question is:

Is this part stj009 same on 1.5Tb samsung HD154UI , i'll buy a used, defective disk because this part, so i replaced it ?
How to know if it's something else burned ? Do you advise me to measure something ?
Three pins that I marked, from right to left, at the same pulse, right ?



Please, any help is welcome.

The MOSFET, coil and diode constitute the -5V supply for the preamp inside the HDA. With the board on the drive, and with power off, measure the resistance between ground and the RHS of the diode. If this resistance is close to zero, then the preamp will be shorted.

You should still be able to measure the Vcore and Vio voltages with the MOSFET out. That should tell you if the board is still partly alive.

I would expect that you should be able to find an equivalent MOSFET at Farnell, RS Components, etc.

_________________
A backup a day keeps DR away.

I measured the resistance before and after the diodes and ground, in both cases is infinite resistance.

I forgot to say this, when I saw that the flames appeared from the MOSFET, i immediately shut down pwr cable from sata connector, but too late....., otherwise, before i removed MOSFET, when the drive is on, i only hear constantly click, click........ until this moment the disk was working really perfect.

The clicking could be due to a servo problem, which would be understandable since one of the preamp's supplies would have disappeared. ISTR another thread where a user had a similar MOSFET problem but was able to recover the drive with a PCB swap. Your preamp is not shorted, so you might be OK. Best of luck.

_________________
A backup a day keeps DR away.

Thanks fzabkar !

I'll try only with replacement 8 pin MOSFET. I'll post here when i start with soldering.
Thanks for support.

Today i checked multimeter, i suspect that is not working as it should, i was right, not working properly.
I found another and i repeated measurements, now look like this. (200 om range on multim.)

0.4 and 142, pcb without mosfet, mounted on hdd with screws.

The cathode of the MOSFET is connected to ground via the coil. The coil is the reason for the low resistance.

See Part 2 of the following tutorial:

Tutorial - Linear and Switchmode Regulators used in HDDs:
http://www.hddoracle.com/viewtopic.php?f=59&t=231&p=596

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A backup a day keeps DR away.

Big thanks fzabkar for the link, tutorial is awesome, very useful information on it.


I ordered a used disc, tomorrow i will have it, so i go to work.

I replaced 8pin mosfet stj009, then i put the disk into the computer. I started, before boot i pressed f12, disk appeared in the list of boot menu, spin up etc, right after that (2-3sec) same mosfet stj009 is burn

A second element which is located before the MOSFET leads to problems.

fzabkar, what causes this, what do you think, do i need to measure some other value ?

Tomorrow I'll have another one mosfet, which part i should also to replace ?



Thanks

This is a photo

You should really test the board on its own before installing it on your drive.

AFAICS, aside from a flaky preamp, the only other culprits could be a leaky diode, intermittent coil (shorted turns), or an intermittent motor controller. It's not an easy fault to troubleshoot. At this stage I agree with Spildit, ie you should consider swapping the PCB, with a "ROM" swap. In fact, if you obtained your MOSFET from a functional donor PCB, then it would have been easier to swap the ROM rather than the MOSFET.

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A backup a day keeps DR away.

Donor pcb is Samsung HD154UI, PCB is damaged, hard disk does not start. I only use mosfet from this pcb.

Just came across this post on a Google search. Thought I'd add my findings for anyone interested.

I had the same problem - in my case, it's an older 320GB Samsung with a blown STJ009 MosFET. Looks like the original owner also made a mistake with connecting/disconnecting power on the unit.

Anyhow, I've repaired this HDD for anyone interested.

I replaced the STJ009 with a NDS9953A. HOWEVER, the NDS9953A is a dual mosfet configuration as opposed to the single mosfet in the STJ009 - pin 2 is connected to the gate of the first mosfet in the NDS9953A as opposed to the source in the STJ009. To use the NDS9953A in place of the STJ009, I simply lifted pin 2 of the IC (not soldered to the board) and wired it to pin 4. All other pins soldered as usual.

HDD is alive...

I take no responsibility for anything though!