HDD repair - burnt PCB

[Half-Saint]

A guy brought in three external hard drives, all three died on the same day. He claims that he just moved all the equipment downstairs to another room. Magic?

Anyway, two hard drives show no physical damage, they just won't start up or turn on. The third one is a Samsung HD103SI 1TB 3.5" model. There's some obvious damage to the PCB but I'm not sure what's what.

The large SMD components near the power connector that appear burnt have markings LG. 951. Not sure what they are. There's also a micro component on the right side of LG 951. The one on the left has similar markings ON 951 and 6V8A under that.

Google says that these are TVS diodes. Is there any way to test them? I'm hoping that I'd be able to repair the hard drive by replacing both diodes.

Thanks for any help you can provide

EDIT: I just tested both diodes with the multimeter (continuity test) and the one on the right that only says LG 951 beeps both ways. The one on the left doesn't beep at all.

[stj]

Re: HDD repair - burnt PCB

most likely,
he mixed up his psu's when he moved the drives,
then plugged them all into a wrong or fucked psu.

you should ask him for the psu's if you dont have them yet!

[Duncanbest]

Re: HDD repair - burnt PCB

FROM
http://fidestec.com/blog/disco-duro-resucitado/

marking LG --> 1SMB13AT3G



marking 6V8A --> P6SMB6.8AT3G

[Half-Saint]

Re: HDD repair - burnt PCB

Thanks mate I had to run it through google translate but it helps a lot :-)

So far I removed the "beeping" TVS and hoping that'll be enough for me to get the data off. After that I'll try actually repairing the drive.

[Half-Saint]

Re: HDD repair - burnt PCB

Success! Desoldering the burnt TVS brought the disk back to life and I'm copying data off of it right now. I've already ordered several replacement diodes for possible future use.

Thanks for the help guys :-)

[Half-Saint]

Re: HDD repair - burnt PCB

I ordered a few of those:
http://si.farnell.com/on-semiconduct...13?Ntt=1459013

Soldered a new diode and it doesn't work. Did I get the right diode? Could it be that the orientation is wrong? The white line is turned towards the power connector.

[R_J]

Re: HDD repair - burnt PCB

The diode you installed is a 5 volt protection diode, that will conduct (short) at 6.4 - 7 volts, the connector has +12 volts at that pin so the diode most likely shorted.
You need a 1SMB13AT3G for the one marked LG and 1.5SMC6.8AT3G for the one marked 6V8A

[R_J]

Re: HDD repair - burnt PCB

This should work for the one marked LG http://si.farnell.com/jsp/search/bro...questid=186158

[Half-Saint]

Re: HDD repair - burnt PCB

The other diode is fine, I only need to replace the one on the right (LG 951).

There's so many different diodes I obviously got confused and ordered wrong diodes

[R_J]

Re: HDD repair - burnt PCB

It looks like the 951 is the date code, the diode is for protection so if the original diode was shorted I suspect the power supply that was connected to it before was faulty,the + 12 volts must have been over +16v to short the diode.
You could check the 12 line on the other 2 drives for a fault, they may be repairable also.

[Half-Saint]

Re: HDD repair - burnt PCB

OK I'm back trying to fix this. Would this do?

http://si.farnell.com/bourns/smbj12a...ditmatch=rel_3

[Half-Saint]

Re: HDD repair - burnt PCB

Replaced the diode with the one from the above link and everything works just dandy.

Cheers guys