Unusual drive failure - 12v line short

I have a PVR thingywotsit on my TV. Today it died, no power. Listen to
PSU - tick, tick, tick. Ah, thought I, bad caps.

But no, the cause was the hard disk - the 12v line was completely short.
I've not seen this mode of failure of a hard drive before now; has
anyone else?

Western Digital model WDC2500BB-00RDA0, 250GB.
date on drive: 25 Jul 07, out of warranty

Stuck in a 160GB IBM from my bits box and off we went.

It may be relevant that the drive is on 24/7. I cannot find any specs
for expected longevity or MTBF on wdc.com.

--
(\__/)
(='.'=) Bunny says Windows 7 is Vi$ta reloaded.
(")_(") http://imgs.xkcd.com/comics/windows_7.png

But no, the cause was the hard disk - the 12v line was completely short.
I've not seen this mode of failure of a hard drive before now; has
anyone else?

Maybe a capacitor across the 12V line died. RIP.

But no, the cause was the hard disk - the 12v line was completely short.
I've not seen this mode of failure of a hard drive before now; has
anyone else?

Yes. Unusual, but it does happen.
In this case, the extra current has just caused the PSU to trip out.
Most times, there is enough spare capacity in the PSU to vaporise the
part that's failed, and whatever device it is just power cycles and
comes back with the disk dead.
Cheers.

On Sun, 7 Jun 2009 16:17:44 +0100, Mike Tomlinson
wrote:


I have a PVR thingywotsit on my TV. Today it died, no power. Listen to
PSU - tick, tick, tick. Ah, thought I, bad caps.

But no, the cause was the hard disk - the 12v line was completely short.
I've not seen this mode of failure of a hard drive before now; has
anyone else?

Western Digital model WDC2500BB-00RDA0, 250GB.
date on drive: 25 Jul 07, out of warranty

Stuck in a 160GB IBM from my bits box and off we went.

It may be relevant that the drive is on 24/7. I cannot find any specs
for expected longevity or MTBF on wdc.com.

Most modern drives (within last 5 years or so) have a very
long expected lifetime (MTBF = 250,000 hrs = 28 years
running 24/7, and 500+k hours is more typical today).

You will most likely replace the drive within 5-7 years due
to capacity (drive nearly full?--replacement drive costs
$100 and is 5-10 times capacity--or more) or you might buy a
new system with a new (larger) drive, OS, programs, etc.

Also, the speed (read/write and/or transfer) of new drives
(making backups of large files, etc) might be significantly
faster, so you buy a replacement for that reason.

Therefore, it is likely the drive will be replaced for a
number of reasons other than it died.

Mike Tomlinson wrote:

I have a PVR thingywotsit on my TV. Today it died, no power.
Listen to PSU - tick, tick, tick. Ah, thought I, bad caps.

But no, the cause was the hard disk - the 12v line was
completely short. I've not seen this mode of failure of
a hard drive before now; has anyone else?

Yes, usually due to a capacitor across that rail as a filter shorting.

Not common, but not unheard of.

Western Digital model WDC2500BB-00RDA0, 250GB.
date on drive: 25 Jul 07, out of warranty

Stuck in a 160GB IBM from my bits box and off we went.

It may be relevant that the drive is on 24/7.

Nope. They get used like that a lot.

I cannot find any specs for expected longevity or MTBF on wdc.com.

The specs are pretty sparse on there now but they are typically 250K hours on consumer drives like that.

In message , Ato_Zee
writes

But no, the cause was the hard disk - the 12v line was completely short.
I've not seen this mode of failure of a hard drive before now; has
anyone else?

Maybe a capacitor across the 12V line died. RIP.
More likely to be a transorb but most likely to be the motor driver IC.
--
Clint Sharp

In comp.sys.ibm.pc.hardware.storage Ato_Zee wrote:

But no, the cause was the hard disk - the 12v line was completely short.
I've not seen this mode of failure of a hard drive before now; has
anyone else?

Maybe a capacitor across the 12V line died. RIP.

Had a Dell laptop with that problem; capacitor across the 19vdc power
input shorted, so capacitors do fail that way.

Jerry

On Sun, 7 Jun 2009 16:17:44 +0100, Mike Tomlinson
put finger to keyboard and composed:

I have a PVR thingywotsit on my TV. Today it died, no power. Listen to
PSU - tick, tick, tick. Ah, thought I, bad caps.

But no, the cause was the hard disk - the 12v line was completely short.
I've not seen this mode of failure of a hard drive before now; has
anyone else?

It's common enough. There will probably be two TVS (transient voltage
suppression) diodes, one across the +5V rail, the other across the
+12V. You can remove the shorted diode and the drive should work
without it. Just make sure your power supply is good ...

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

In article ,
Gerald Abrahamson wrote:
:
:Most modern drives (within last 5 years or so) have a very
:long expected lifetime (MTBF = 250,000 hrs = 28 years
:running 24/7, and 500+k hours is more typical today).

The units for MTBF are not hours but device-hours, i.e., the product of
the number of hours and the number of devices being observed, and that
rating applies only during the device's rated service life, which is an
entirely separate parameter.

MTBF of 250,000 is almost totally unrelated to the expected service
life. It is quite possible to have a device with its MTBF 250,000 and a
rated service life of 1 hour. It just means that if you ran 250,000 of
those devices for one hour you should expect 1 failure. Once a device
passes its rated service life, the MTBF rating no longer applies.
Think: a battery used to provide power to a missle's guidance system --
built to be highly reliable for the short time it's needed, and pretty
much assured to go dead not long after that. High MTBF, short service
life.

Looking at the power-on hours and corresponding normalized SMART value
on a few fairly recent drives, it appears that the SMART warning due to
power-on hours would come at about 10 years of power on.

--
Bob Nichols AT comcast.net I am "RNichols42"

In comp.sys.ibm.pc.hardware.storage Gerald Abrahamson wrote:
On Sun, 7 Jun 2009 16:17:44 +0100, Mike Tomlinson
wrote:


I have a PVR thingywotsit on my TV. Today it died, no power. Listen to
PSU - tick, tick, tick. Ah, thought I, bad caps.

But no, the cause was the hard disk - the 12v line was completely short.
I've not seen this mode of failure of a hard drive before now; has
anyone else?

Western Digital model WDC2500BB-00RDA0, 250GB.
date on drive: 25 Jul 07, out of warranty

Stuck in a 160GB IBM from my bits box and off we went.

It may be relevant that the drive is on 24/7. I cannot find any specs
for expected longevity or MTBF on wdc.com.

Most modern drives (within last 5 years or so) have a very
long expected lifetime (MTBF = 250,000 hrs = 28 years
running 24/7, and 500+k hours is more typical today).

The MTFB is completely untelated to the device lifetime.
It just describes the failure probablility during the device
lifetime. Device lifetime is stated in the device datasheet
and typically 5 years.

For example, an MTBF of 250'000h gives you a failure
probability of 365*24/250'000 = 3.5%/year, in the first
5 years. It dioes not make any statement about the failure
pobability afterwards.

Arno