Hi,

I have a Hitachi Deskstar HDS721680PLA380 80gb that is not spinning at all, i opened the hard drive to view if it's jammed but it isn't.

This case is kind of strange because normally when a hard drive sounds no spinning can be head stick on the platters or a difficult platter jammed.

So now i'm maybe thinking of replacing the HSA because of the Preamp

Ok, is there a question here ?

Also it could be TVS diode. Did you open it in a clean room? You may have damaged the drive by opening it if you are not experienced.

If data is important, better taking it to a DR company. Otherwise you might need to further troubleshoot the PCB, post some good quality photos

If you upload a detailed photo of the PCB, I could help you locate the voltage test points.

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A backup a day keeps DR away.

Actually it was opened in a clean room thanks for concern, and these are the pictures of the pcb.

See viewtopic.php?f=1&t=27980

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A backup a day keeps DR away.

Oh jesus that's a huge post lol

Thanks for the help i'll see the :3

Hard Disks are an extremely complex unit, the more you learn about them the more you are amazed at how much is going on in that little box with few parts.

I have a 128gb hatachi sata hdd which not detects my system & not spins ihave check its tvs diods these are ok then what will be the problem,can any body send me its normal voltages at different places which can help me or can any body send me its schematic diagram thanks in advance

Hi,

I was reading your article and appears to be the R5 resistor because it's not measuring 0.47 ohms and all the test points on the HDA are okay. I'll try to find help with someone that have more knowledge about electronic. Also i could try migrating the ROM of the PCB to a donor one i think.

I would measure the resistance between ground and the preamp side of R5, with the board on and off the drive. This will tell you whether the preamp is shorted.

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A backup a day keeps DR away.

Maybe i'm wrong but it measured around 41 kohms, btw. Just now i repaired another pcb with this one (i migrated the D3 diode to get another pcb working again) and with the repaired pcb that successfully works the hard drive is doing me the same. I haven't migrated rom but the hard drive is suppose to do something different as i know with some experience.

I'm starting thinking about the preamp of the drive.

What voltage do you measure on each side of R5? Is it +5V on one side and 0V on the other? What is the actual resistance measurement for R5?

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A backup a day keeps DR away.

i have +5v in both sides of R5, and the resistence cannot be measured, i have continuity on both sides of R5 looks like open.

I measured on other pcb that i have and it's different +5v on one side and 0v on the other side of R5, also the resistance it's near 0 and i don't have continuity.

Looks like the R5 is not working well.

Your terminology is confusing. Perhaps you should ask for more help from your friend.

However, if R5 is open circuit, and if there is no short circuit in your preamp, then replace R5 with a 100mA fuse, or just swap the PCB and transfer the NVRAM.

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A backup a day keeps DR away.

Hi again,

I got a donor drive with the same specifications, swapped PCB and also ROM and still the same with the known good PCB. The only thing that i can see now is maybe a preamp problem.