root Inscribed thus:

Baron wrote:
root Inscribed thus:


I got a used computer on Saturday at a yard sale. I bought
it for the case, although it came with a motherboard and power
supply but no drives or video card.

I put a video card into the machine, along with an IDE drive
and the system ran fine.

I replaced the motherboard with one known to be good: I pulled
it from a working computer. I wanted to be able to use SATA
drives in the "new" case. The power supply did not have any
SATA power cables so I used the molex-sata power adapter cables.

When I turned the system on with the first SATA drive in
the system a component on the drive smoked and the
drive is dead. The component is a surface mount plastic
two-terminal (I think) device about 1/8 x 3/16 inch.
I can just barely read C651 on the device.

I swapped out the power supply for a second unit,
and put in another SATA drive. I checked voltage to the
molex and it was 11.86 volts and 5.09 volts.

It happened again, when I turned on the power I killed
the second SATA drive.

I took my motherboard out of the new case and put it
back in the my old case. Everything runs fine.

I put another power supply in the "new" case, this
power supply did have SATA power cables. Back into
the case went my motherboard. Again, upon power up
a third SATA drive was blown. The SATA cables coming
from the power supply had an extra orange wire that
the molex adapter cables do not have.


Three SATA drives down the drain. IDE drives work
fine.

The last drive that burned up had only the SATA
power cable connected. That means the motherboard
is out of the picture.

I have run out of expendable SATA drives. Any idea of
what might be the problem?

Possibly open circuit grounds on the power connector...


Using my last expendable SATA drive, I retraced my steps
as closely as I could remember what I did on Saturday.
Starting with the original MB that was in my new case,
I put back the original power supply, and plugged in the
SATA drive. No Problem. I used the same Chinese SATA adapter
cables as I did. I have no idea of what the problem
might have been since it is not reproducible.

It might be that, in my haste, I didn't push the SATA power
plug all the way in and it might have been askew.
This is really a stretch because I have pushed on
SATA cables for a long time, and I would have had
to repeat that screw up two more times.

The mental picture was of an OC ground could put 7volts on the drives 5V
rail. As an aside I suspect the device which let out the smoke could
have been a transient voltage protection device. A bit like a pair of
back to back zener diodes. These tend to go SC when they fail.

--
Best Regards:
Baron.