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 Post subject: Seagate Diode Info needed- PLEASE HELP!
PostPosted: November 7th, 2008, 12:25 
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Joined: November 7th, 2008, 12:04
Posts: 5
I have a Seagate ST3400633A hard drive, with Firmware:3.AAJ, PCB P/N 100373051 Rev A.
One fuse diode went bad, there is no resistance when I measure Ohms both ways. Diode says "KVP 65A" and it black color, located on PCB next to the power connection and right next to the side of diode, next to the "U" cutout. The manufacturer logo is similar to Texas Instruments, (overall shape), and without lettering. How can I find the values for the diode(Voltage, resistance)? I called Seagate, and they don't have that info.


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 Post subject: Re: Seagate Diode Info needed- PLEASE HELP!
PostPosted: November 7th, 2008, 12:33 
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Joined: November 7th, 2008, 12:04
Posts: 5
Here is the pic of the diode location. I borrowed the pic from another topic here, but the board is exactly the same.


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 Post subject: Re: Seagate Diode Info needed- PLEASE HELP!
PostPosted: November 7th, 2008, 13:57 
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Joined: December 23rd, 2006, 16:08
Posts: 938
Location: NJ
Instead of Ohms, measure with Diode check. Most multimeters have a diode check setting.


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 Post subject: Re: Seagate Diode Info needed- PLEASE HELP!
PostPosted: November 7th, 2008, 13:58 
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Joined: November 7th, 2008, 12:04
Posts: 5
Found out that I have to remove it, then the one question left is what can I replace it with? I found a link to Digikey part, but that one is a 5v. and I need a 12 volt.


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 Post subject: Re: Seagate Diode Info needed- PLEASE HELP!
PostPosted: November 7th, 2008, 14:13 
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Joined: December 23rd, 2006, 16:08
Posts: 938
Location: NJ
How did you find out you need to remove it?

If it's a TVS, you can just remove it if you're bold. However proper repair starts with PROPER DIAGNOSIS. A good Diode, or TVS, will show up as an open on most multimeters, hence the Diode check.

It might be helpful to know if you're trying to return the drive to service, recover data, or something else.


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 Post subject: Re: Seagate Diode Info needed- PLEASE HELP!
PostPosted: November 7th, 2008, 15:28 
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Joined: November 7th, 2008, 12:04
Posts: 5
I have read other topics, they all pointed to this TVS.
This TVS isn't open, I checked it when took it out, it is shorted, and I got 0.000 ohms of resistance.
I am trying to just recover data, and hopefully still be able to use the drive. It was in external case with warranty, but I needed data, so I broke in to the case, and got the drive out. Warranty is void. So now I am trying to find the same 12v TVS diode.

I checked this diode with help of electrician, he confirmed that it failed.


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 Post subject: Re: Seagate Diode Info needed- PLEASE HELP!
PostPosted: November 7th, 2008, 15:44 
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Joined: July 18th, 2006, 3:05
Posts: 7532
Location: ITALY
Remove it. If drive starts up normally, backup your data then we will think what to do later. If not, the drive needs to be repaired. Period.


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 Post subject: Re: Seagate Diode Info needed- PLEASE HELP!
PostPosted: November 7th, 2008, 15:49 
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Joined: December 23rd, 2006, 16:08
Posts: 938
Location: NJ
Agree. Just don't power it up from the same external power supply. If you want to return the drive to service, any 12V TVS will work. Junk drives are a good source. You might want to replace the other TVS that looks like it was removed. Then again, you might just be better off junking the drive after getting the data. Drives are cheaper than data recovery :)


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 Post subject: Re: Seagate Diode Info needed- PLEASE HELP!
PostPosted: November 7th, 2008, 16:03 
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Joined: July 9th, 2008, 15:42
Posts: 85
rchadwick wrote:
You might want to replace the other TVS that looks like it was removed.


I don't think it is his exact PCB dude.

andrey_2004 wrote:
I borrowed the pic from another topic here, but the board is exactly the same.


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 Post subject: Re: Seagate Diode Info needed- PLEASE HELP!
PostPosted: November 7th, 2008, 16:20 
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Joined: November 7th, 2008, 12:04
Posts: 5
The one the arrow is pointing to is the one that is messed up. My 12v line was short, so its that TVS. Anyway, I removed it and the drive powered up! I'll get the data off. After, I have found a 12v diode, although the rated wattage is higher, here is the info off the diode:
Fairchild semiconductor: 1V5KE15(C)A
Reverse Stand-off Voltage: 12.8V
Breakdown Voltage Min 14.3V Max15.8V
Test Current: 1mA
Clamping Voltage: 21.2V
Peak Pulse Current: 71.0A
Reverse Leakage: 5uA
Here is the link to datasheet.
http://pdf1.alldatasheet.com/datasheet- ... KE11A.html

If you guys dont' think this will work, please let me know, the electrician said that the diode will be "looking" and the voltage, so if wattage is rated higher, it will be fine, as long as its higher.


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 Post subject: Re: Seagate Diode Info needed- PLEASE HELP!
PostPosted: November 7th, 2008, 18:45 
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Joined: July 16th, 2008, 17:52
Posts: 490
Location: Long Beach, California
the safest way to replace TVS is to look around and get an identical pcb and just swap one of the TVS of it on to yours, this insures that the same specced TVS is used. This will cost you more though...


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 Post subject: Re: Seagate Diode Info needed- PLEASE HELP!
PostPosted: November 7th, 2008, 18:48 
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Joined: July 18th, 2006, 3:05
Posts: 7532
Location: ITALY
Your "replacement" is not 12V. Anyway the case is closed... and your electrician is WRONG. TVS does not have "wattage", tell him that it's not a ZENER . PEAK PULSE CURRENT is a completely different thing and... oh, I don't get paid for teaching HERE. Timeout.


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