Hard disk Logic board problem

[sujaypaichar]

Hi friends, I dont know what happened, but when i switch on my pc, there was smoke coming out from cpu. When i checked it out i found that one of the component in the logic board is burnt. But other all parts are good except the power input slot( which i can fix the whole power slot by some other HDD's slot). When i took the hdd to repair shop, they told that it is a diode which burnt out because of short in the power cable. They also told that new logic board is very costly and u can buy a 2nd hand 80 gb HDD with that. But if i get the component, they will be able to repair it. So guys, do u have any other solution???

HDD is SEAGATE

Model no : ST3802110AS

Firmware: 3.AAE

It is 80 GB SATA- 7200 RPM

Thanks.

In the image,

A- Burnt diode

B- This is the component which is same as the burnt one

C- Burnt power slot which i can correct it

[sujaypaichar]

The warranty is left till 2011. Since it is burnt, no use of warranty.

[rchadwick]

Search here for TVS. There's a part number to one of them from Digi-Key, and the other can be found with a little effort. These are special diodes that clamp down, and then often burn and short, if the input voltage goes too high. You need one for the +5V line, and one for the +12V line. You also need to spend a few bucks on a decent power supply. Crap supplies don't have overvoltage protection, and a dying power supply can take out EVERY component in a computer. Is that worth saving $10?

Also, no guarantee replacing the diodes will get the drive working. The power supply could have damaged components before the TVS's kicked in.

[sujaypaichar]

I am sure that its not the problem of power supply.

After a long search i found out that the IC burnt is related to 5V and not 12. Because the power pin which is burnt is a input for 5v supply(pin 7 to 9)

[rchadwick]

The picture wasn't clear, I assumed since it was circled, it had some damage. So, just replace the 5V TVS, and you're all set. Actual part numbers can be found by searching for TVS here. Matching exact part numbers isn't terribly important. Just make sure you get a 5V TVS to replace a 5V TVS. You can even grab a 5V TVS from a junk drive. If you need just the data, and you're incredibly sure the PS is 100% fine, and you feel really lucky, you can just remove the TVS, and hopefully it will work. Under these circumstances, I wouldn't risk it. The TVS's tend to go for a reason.

Just curious, what brand Power Supply do you have?

[BlackST]

Sujaypaichar are you Indian or Pakistan by a chance ? In these areas there are tons of extremely poor power supplies, with unstable out, a lot of HF ripple and lots of other problem. Oh by the way they are cheap. You may say... hey, I have checked with a multimeter... but what multimeter ? I have professional, regularly calibrated DMMs and I have 0,1 mV resolution excluding the resistance of the cables, maybe it's not your case, but in HDDs and PCs 5,1 V is a LOT different from 5,15 or 5,19.... next to 5,19 is 5,2 !!!.
And cheap PS have NO overvoltage protection. Only top quality PS (usually on servers and very very high end systems) have electronic crowbar protection that remove INSTANTLY power , all the branches simultaneously.
In your case a spike came out from the PS, and probably (if there are no further damages), only the TVS has limited the damages, absorbing it and breaking himself.
Or maybe the voltage at the part was nearly the clamping voltage CONSTANTLY so the TVS was in the middle of the clamping region and normal operation area, heating up till the fatal spike.
TVS trip only when solicited to and are perfectly reliable, while cheap PS are delivering neverending problems.
Also, old PS with dry caps or - the worst - leaky caps (their ESR rose leading to a chain reaction that has the destruction of the cap itself as endpoint) are time-bombs on PCs.
The quality of the PS can only be determined with oscilloscope, calibrated DMM and with a suitable load condition.