Hellow every one
My Seagate Barracuda LP 500GB ST3500412AS FM CC32
has stoped working , i found out it was pcb problem
the PCB code is 100535704 REV A

I somehow managed to obtain a pcb with same model (ST3500412AS FM CC32)
the only difference is its REV B

i connected the usb adaptor the green flash is turned on but the hdd does not spin
the computer recognies the device but the hdd not appear in the computer
so what could be the problem , could it be a firmware issue or something
i'm new with this any help will be appreciated .

No this will not work plus there is adaptive on the original pcb that have to be moved over to the new pcb. I am a little confussed on your last statement. You say the computer recognizes the drive but it does not spin. What does this mean you can see in your BIOS that the HDD is there and says Seagate on it with name and LBA? Or does this mean when you use your USB connector and plug into the USB port the computer says HDD attached and displays the message but then there is nothing else there?

So if your drive does not even spin with new pcb on it then this can mean an internal problem in the preamp of the head stack assembly. It is hard to tell by what you are saying. Can you attach your original pcb on your donor drive and see if it spins up this will tell you if you have a pcb problem or not on this one. Go this way and report back. But sounds like internal problems on this one for you.

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Iorana Haraharaini

thanks for the reply ,yes the computer recognizes the device ,and says a mass storage device connected , but in device management nothing appears, however when i put my old pcb the green flash will not turn on and it will not spin from here it means definitly a pcb problem , which is due to electric shock or something
However i read on this subject and i aquired some knowledge that,this could be a TVS Diode short ,and i have a multimeter and test the diode which is [TEK] and it read zero , but the new pcb read something else ,
another thing to mention is that , when i put the old pcb , this particular diode become hot quickly.
but if this is the problem why the new pcb did'nt overcome the problem, should i remove the diode or something (because as i read that removing the diode will fix the problem but there is an overvoltage risk or something)
so what should i do here?

If you think it is the 12V or 5V tvs on this then remove it and get off your data as quick as possible. I would be careful because you are no longer protected and if you get another voltage surge this can damage inside of your HDD. Try to take snips and cut it off and see what happens. New pcb does not have correct adaptive to read your drive with it and can not work like old pcb board.

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Iorana Haraharaini

yes was the diode for sure , i removed it and i the hdd spinned and working like the old times and i'm copyimg the data right now.
thank you very very much for your help
i have one more question
if i get the diode from the new pcb and put it on the old pcb , does it work , and safe ?
the old one has a number on it which is 924 TEK but the new one number is 932 TEK will that make a difference.

sorry it is not TEK it is LEK , both of them

Well if you do everything right while replacing tvs from same board, then yes surge protection will be back and you can use drive as previously.

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@sonna22:

Just to answer your earlier specific question:


No difference - the relevant section of the part number is LEK (as you later corrected). On that component, the numbers are usually just the manufacturing date, typically YWW ie 924 = 2009 week 24, 932 = 2009 week 32.

Remember that TVS diodes are not guaranteed to prevent all damage, so even though your drive was usable after removing the damaged TVS, that does not mean that the PCB is totally undamaged after the 12V overvoltage. Premature failure is still a possibility.

IMHO I would only use the drive with that PCB for non-essential data, as it cannot be trusted as much as before the overvoltage; and you also need to investigate why there was an overvoltage at all (I didn't see you explain already if you know why the overvoltage event happened - e.g. wrong PSU used for external disk drive is the "classic" cause).

one day i gave the hdd to my friend to copy some data , he couldn't mention exactly what happened , but he said there is a short in that particular switch that he plugged the hdd power supply to it which also lead to damaging of his nokia n96 phone
sorry about the double post.
thank you so much , i appreciate your help.
my problem is solved