PCB Repair - HDT721064SLA360 - advice needed

[rmy]

Hi,

I need advice in electronics. I got yesterday a non working Hitachi 640GB.

It's spinning well, no particular noise. I first thought it was firmware issue, or wrong PCB exchange before it comes to me.
I asked for the PCB exchange, nothing like that.
I then noticed that nothing happened (I mean no sync noise, no head moove) when hot plugged/unplugged the sata cable.

Looking the PCB whith magnify lenses I then noticed that 2 little capacitors (I think it's caps, but not sure) were missing. They are "in line" just under data connector, on pins 2 and 3.

First question : Are that caps mandatory composants or only for protection ? I mean : May I short them just the time of data extraction ?
Second question : If I need to replace, Does someone knows what's the capacity ?
Last, but not least : There's an external eeprom on the board. If I decide to swap board, I bet eepom swap is needed too there ? Isn't it ?

[einstein9]

post a clear image of the PCB

[rmy]

Hi einstein9,

Thank you for your help.

Here's the pic :

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[einstein9]

Well those 2 missing are a Must, if you are good in Soldering this will not be a problem

did you try to get both back from any dead hard disk?

no need to change your PCB really but those 2 belongs to the DATA

my advice, solder both back

good luck

[rmy]

TY for precicion. I did not try, waiting for advices, because it would have been easier to short

I've a potential donor, I'll try and let you know.

I just wonder how this could have happened, because the disk was inside a computer. They told me it stopped "working", and after that they took it outside the computer.

Perhaps will I face another problem after soldering. I'm quite sure they distroyed the caps while removing the disk…


Edit :

if you are good in Soldering this will not be a problem

Good enough I think. I've already desolder/solder eeproms and a "motor chipset". That's not easy, but with some glue it's easier.

[rmy]

Wooops, one question again, before doing mistakes…

When I unsold TVS, I usually put iron or hot gun to about 280°c (536°F). I wonder if such a temperature would not destroy a so little capacitor.

Is unsolder tape needed there or just hot gun and tweezers should be enough ?

[rmy]

Auto answer : tweezers, iron and little pin are enough.

TY again for advice einstein9 : It's now working fine
Not so easy, but result is'n so bad…

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[einstein9]

hehehe
Man your Soldering is so BAD (reminds me with myself @ the practice time

but good news and good work

[rmy]

[int0x13]

In this case, i wonder how 2 SMD caps like that could unsolder themselves in a computer case? Because the OP said after replacing the 2 caps the HDD was fixed.

[biggerpizza]

In this case, i wonder how 2 SMD caps like that could unsolder themselves in a computer case? Because the OP said after replacing the 2 caps the HDD was fixed.

It's not very possible. I guess someone took them off.