Tell me more ×
Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. It's 100% free, no registration required.
up vote 1 down vote favorite

I found an old 15 GB HDD lying around in a pile of spare computer parts. I decided to see if it would still work because it could be an emergency backup. So I plugged it into my ATX PSU only to find one of the chips on the board had several holes in it glowing red hot and it was smoking. A catastrophic failure! But why? What could cause the IC to fail so badly? The IC glowed for about 30 seconds before the supply tripped off. I have no idea on the circumstances of this failure - I did not do extensive tests, and I didn't examine the drive beforehand.

It was something like this, http://www.youtube.com/watch?v=ni_PA0as47g, but a different IC, and a different drive.

share|improve this question

2 Answers

up vote 5 down vote accepted

I guess it could be a lot of things, anything that causes a short inside any IC could cause this, maybe a high ESD spike hit the IC and it fused some of the transistors. But if I had to venture a guess in regards to the video:

That IC is the motor driver for the spindle motor and that location on the IC is where the drive transistor is located. The IC is controlling 12V to the motor and a computer power supply can provide a lot of current at 12V, supply in my computer has 4 25A +12V rails.

If something had happened to the spindle motor that locked it in place, the drive current would be massive (think the start up current for a DC motor but never reducing once its spinning). The current was enough to push the drive transistor past its thermal breakdown point and it got hot enough to melt the IC package, resulting in the hole and the glowing.

share|improve this answer
Hmm yeah, good theory on the video. I think the chip that burnt on mine was the IDE controller, as it has loads of traces going to the IDE connector. – Thomas O Nov 13 '10 at 22:48
your average computer supply can provide ~150W of power at +5V also, almost impossible to guess what caused the short inside the IC but unless there was obvious damage i would assume that ESD hit it and fused some transistors causing the sort. – Mark Nov 13 '10 at 22:52
some more entertainment: youtube.com/watch?v=JCPXckfT-6g&feature=related I think exploding aluminum caps are my favorite – Mark Nov 13 '10 at 23:05
up vote 3 down vote

If you were using really old IDE cables without the bump to position it properly, it's possible you were off by a row/column of pins. I did this once in a highschool computers class and it definitely burned something on the drive, smoke and all.

share|improve this answer
Good suggestion, but I didn't connect the drive to anything except the power supply. – Thomas O Nov 14 '10 at 0:45
Whoops, missed that. – pfyon Nov 14 '10 at 15:52

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.