WD2500BB Caviar blowing the 12V TVS – cant find the reason

[AVS]

Hi Gurus!
Please help me to find out why my WD 2500BB Caviar is shortening the 12V TVS.
S/N WCANKF108324
model: WD2500BB-14RDA0
DCM: HSBHCTJAHN
Thailand made
One day the computer won't start, HDD disconnected and it is came back to normal operation.
So I found that 12V TVS is open in both directions and 5V one is normal. I replaced the burned one, and turn comp on and same happened it is open again... I do not know a lot about this electronics parts - just a little...
Please help me if it is possible to find the reason, or may be this drive is dead forever. Any way the warranty on this drive just expired, info is valuable to me but in worse scenario I will give up though I cant pay 1000$ for recovery any way. If some one can help me to fix it will be great.
Waiting for reply,
regards to everybody who will answer
Anatoli

[AVS]

Hi,
I just want to add that without this TVS drive spins, and I assumed that I can recover the data from it, thanks God. Major problem is solved, but I can't understand what is happening when I'm replacing the 12V TVS and it is blowing open again and again...
Any idea? Is it possible to find the TVS exact one? I just used one at 12V, 500W, single direction, surface mount but I do not know what the closing voltage should be? Any one can help?
Thank you

Last edited by AVS on May 12th, 2009, 23:16, edited 1 time in total.

[drc]

My first guess would be your power supply.

[AVS]

Hi, thank you for the answer, I just try it, it works fine with other HD, but any way I replaced it since this failure happening for reliable one - Hercules 500W is the current one, brand new.

[N.C.]

AVS,

Your PowerSupply shortening the TVS, not the drive itself.

The TVS is good for suppressing the "bad things" wich can come from the power line.
It is shorting if the voltage gets under -0.5V or upper than 13.5V (if i remember rigtht the limits).
Your PS is a tricking one!
Immediately replace the PS, and the drive (or a TVS for a same type if you can)....

Additionally, a general suggestion:
Don't use a PS/drive wich is older than 2 years, if you want to avoid an expensive recovery...

Janos

[AVS]

Thank you guys!
I found this forum very helpful and red almost everything trying to get the answer.
My special thanks to N.C. and Spildit for the advises. So I did replace the PSU - it is brand new now, but I couldn't find anything wrong even with my old one, measured outputs it is steady 12V and 5V ... and other drive works just fine connected to this one - but I do not taking risk any more and will give it up. I am aware (Thank you guys again I got this from the forum and other internet places) that TVS has a polarity so I did connect same as it was shown on the board plus and minus. At least same way as original one was. Then I took new TVS and solder it back instead the open one, turn NEW PSU "on" and herd light sound - tk.. - and everything is off again and TVS is open again. But as I told if I remove TVS - I was able to back all my data so - I'm safe, Thank you all! If some one knows what I need to check to refurbish the drive - will be very helpful - if it is too much to ask - I will forget about it.
Thank you! Regards and respect!

Anatoli

[jpllal]

There is most likely a filter capacitor attached to the TVS that is shorted to ground. Replace the capacitor and the TVS at the same time.

[N.C.]

There is most likely a filter capacitor attached to the TVS that is shorted to ground. Replace the capacitor and the TVS at the same time.

Disagree, the TVS are connected parallel to the power line, not serial.
This can't short the TVS.

Janos

[jpllal]

Parallel or serial it doesn't matter, if the anode of the diode has 12v and the cathode is shorted to ground, via a shorted out capacitor for example, the diode will burn up.

[BlackST]

BULLSHIT. IT'S NOT A FUSE. THERE ARE NO PARALLEL OR SERIAL TVS BUT MONO OR BIDIRECTIONAL.

[N.C.]

Yes, this is what i tried to say.
The TVS is not FUSE!
This is an independent protection unit.
Not depends on any capacitor or any other component on the pcb.

Janos