WD External hard disk failure...

"Jay" bravely wrote to "All" (13 Dec 05 13:09:31)
--- on the heady topic of "WD External hard disk failure..."

Ja> From: "Jay" <>
Ja> Xref: core-easynews comp.sys.ibm.pc.hardware.storage:288636
Ja> sci.electronics.repair:351238

Ja> I have a Western Digital 160 GB External USB 2.0 HDD (Model #
Ja> WD1600B008-RNN). It was working well and good and suddenly it stopped
Ja> working when I wasnt around. My brother was using it and he says he
Ja> may have changed the polarity for the DC input. I had a DC adapter
Ja> which can accomodate multiple heads. I changed it to right polarity and
Ja> switched it on.

[,,,]

When a reverse polarity is applied to some IC's, if they aren't
destroyed outright then they might sometimes store a charge that
impedes them from working again when the proper polarity is applied.
Sometimes leaving it alone for a couple of days will naturally
discharge the semiconductor layers so that it then can function again.
This has happened to me a couple of times and luckily no damage done.
It may seem like the device is dead but if there was no obvious smoke,
give it a little time, sometimes it does clear up on its own.

A*s*i*m*o*v

.... Just a little force field zap.

 

That is just plain wrong. One approach is a diode across each
of the two voltage rails to ground which will short the rail when
the voltage is reversed. That should shut down the power
supply and protect the device.

 

Ok, updates:

I opened the enclosure and checked inside. There was no blown out fuses
or infact nothing remotely resembling a damaged part.

As Ive been thinking, the lights are lit when the power source is
plugged, and the supply for the lights are after the voltage regulator.
So i'm thinking something bad has happened to the drive it self. I
didnt get a chance to test whether the supply goes to the motor or not,
which i will do today.

Also I'll check whether the drive works when I connect it to a PC, else
I guess I'm screwed big time ((( Professional data recovery is $100 a
gig ((

 

oh btw, the error in the device manager says Code 10- the device cannot
be started.
I run a Win Xp SP2 machine and I tried again by updating it with latest
USB 2.0 drivers, no luck!!

 

There isnt usually anything visible when its a reversed supply that
has killed a device. Not always tho, I have seen an optical drive
produce smoke when some eejut rammed a conventional molex
power connector on backwards with an internal drive.

Sure, but that doesnt mean that the electronics isnt dead.
You can get a situation where the leds are fine since they dont care
about a reversed voltage, but what is driving them has got fried.

Yeah, that's quite likely given that some of the external
cases dont even attempt to regulate the main supply to
the drive, so it gets 12V reversed if you have the head
reversed on the external power pack.

It isnt hard to design the 5V regulator so that
it doesnt die when its input 12V is reversed.

Yeah, could well be.

Yeah, but it isnt clear if that means the
drive cant be started or the bridge is fried.

Yeah, I wouldnt have expected that to make any difference.

Not always, http://www.retrodata.co.uk/
Worth the hassle if the alternative is attempting it yourself
because the in country recovery is too expensive to contemplate.

 

| Also I'll check whether the drive works when I connect it to a PC

Really, that's one of the first things you should try when an external
USB or firewire drive fails.

| else I guess I'm screwed big time ((( Professional data recovery
| is $100 a gig ((

It's not always that expensive, but it's always expensive. One of
many reasons why backups are important.

(Other reasons? Sometimes, even the professionals can't get your
data.)

 

That seems rather low. I would expect it to be far more expensive,
like 10-50 times more expensive.

Arno

 

With respect, do you know what a surface mount fuse looks like?

Dave

 

Yes I do. Matter of fact there was no surface mount fuse, but it had
PPTC Resettable Fuse inside, thats why it didnt blew.

 

There isnt usually anything visible when its a reversed supply that

Thanks for that cheerful start

Yeah may be, but that takes away the blown fuse part out. So may be the
controller board got fried.

It had a voltage regulator, so I think it was safe that way.

Will go home and do the rest of testing today

Thanks everyone!!

 

Yes Dave, I do. Also, I had PPTC resettable fuse in the circuitry, so I
guess it will not blow.

 

I got a multimeter from work today...checked all the voltages and
currents, its all perfect, uptill the point where it goes to the HDD

Ill try mounting this drive thro IDE on a PC and let know how it
goes...

This goes on and on for ever..I dont have a PC at home, so need to take
it to work to check

Slowly my hopes of recovering the data by myself is fading away...

 

Also, the design is very well put, it had a voltage regulator and I
also tried reversing the polarity, the Voltage/current never got in to
the circuitry at all. I think that the resettable fuse works like a
charm!

 

That doesnt explain why it doesnt work
with the power the right way around now.

 

Listen to the man who said

"Buy an identical working drive and swap the controller board to recover
your data."

Chances are you will get lucky.

I know that there is one chip inside the drive chamber, a multiplexer
for head selection and or amplifiers. It's fairly far from the impute
power so it has a chance of survival.


Hugh

 

I see. Good luck with the drive.

Dave

 

Yes, I will know it tonight. Im plugging it in my friends computer

*crossing my fingers*