SAMSUNG hd753lj with fried ROM -Please help me to solve it

[alan_aguinaga]

Hi everybody! This is my first post and I would like to share a solution to recover my PCB and data soterd on my hdd.

The TVS Diode is short and I remove it a long time before, but now I have a problem on my drive as you can see on pics posted below

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[drc]

That's not a ROM

[rameez]

Post full picture of your pcb then we will tell you where ROM is .

[phishin_ca]

This is a good example of why you never run the drive again after recovery. Especially not without the TVS!

[dick]

This is a good example of why you never run the drive again after recovery. Especially not without the TVS!

Yes, and I would either junk the psu or the power control circuit to the drive. Otherwise the replacement will go up in a similar puff of smoke.

[alan_aguinaga]

OK, I'm not shure it was a ROM chip. I think that its an voltage regulator.

What chip can I replace for the fried one ? It was ST... (model was fried)

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[alan_aguinaga]

I don't think that PSU was the guilty. It's good coolermaster 1000W etc. It think that Thermaltake's BlacX doc station do a half of dirty job beside capacitor I put in place of dead TVS as you can see in PCB's pics

[networkpc3000]

this hard to done by yourself.

[fzabkar]

That could be a MOSFET, or a switchmode regulator that incorporates a MOSFET.

The flywheel diode is a B240 Schottky.

B240, 2.0A, 40V, Diodes Inc, SURFACE MOUNT SCHOTTKY BARRIER RECTIFIER:
http://www.diodes.com/datasheets/ds13004.pdf

The mark on the chip looks like a dab of paint or liquid paper. I don't think I've ever seen a chip fail that way.

That particular regulator appears to supply the negative voltage for the preamp.

What was the failure symptom?

[alan_aguinaga]

It stopped to be detected by BIOS and when I remove it this chip on PCB was fried.

I can do repair on this PCB. I will put my progress here and all help will be welcomed

[fzabkar]

Here is a datasheet, with application circuits, for a typical motor controller chip:
http://www.datasheetarchive.com/pdf-dat ... /28826.pdf

I would check whether the preamp is shorted. This could take out the negative voltage regulator. Follow the bottom end of the 1R2 coil to the 20-pin preamp connector. I believe that should be the negative rail. The ground should be easy to find.

This article should help you identify the components:
http://hddscan.com/doc/HDD_from_inside.html

[fzabkar]

See this photo:
download/file.php?id=1386&mode=view

The mystery part is an STJ009 MOSFET.

STJ009, 30V, 5A, P-channel Trench MOSFET, AUK Corp:
http://www.lintry.com.cn/spec/17/STJ009.pdf
http://www.datasheetarchive.com/pdf-dat ... -24387.pdf