Hitachi 750gb suspect pcb problem

[El Stino]

Hi everyone,

It’s my first post here so please forgive me if I get something wrong.
I have done some prior research.

I’m having trouble with a 750gb Hitachi HDT721075SLA380

Full specs:
S/N: MG072UHA
MLC/ BA3013
0A29840
BA2922A
SEPT 2008

The drive comes out of a LACIE usb external case and didn’t show up on the computer anymore. The drive did not fall or anything so I do not suspect any fysical damage to the drive itself. I took the drive out of the external case, removed the usb interface and hooked it directly to my motherboard using SATA cable. At this point I noticed the drive doesn’t spin up and doesn’t show up on the computer.

I did buy several of these external drives at once and took the pcb of a drive with same model and MLC code and mounted it on the faulty drive. At this point I was unaware the firmware codes on Hitachi pcb should also match up, wich they did not (0A29894 BA2950B), but now the drive spins up normally, no abnormal sounds, but still doesn’t show up, I assume from the pcb code difference.

Is there anything I can still try with this non perfect match or do I need to find an exact match? What should my next step be? I’m in no rush to recover the data, I wanna make shure I do this right as I feel the drive itself is still ok.

Any suggestions are welcome

[einstein9]

get back to your original hdd PCB

with basic electronics testing issues, have a look @ this image and try to test the components here
as described here on this image

http://www.users.on.net/~fzabkar/HDD/HD ... 60_TVS.jpg

thnx again to fzabkar for providing such tips here


Note:

disconnect the PCB from the HDD, attach Power to it, and start diagnose/test

good luck\

[El Stino]

So you are saying I should measure the voltage over these components as on the photo?

[networks]

El Stino what einstein9 is trying to tell you that the symptom of the drive not spinning up can be the TVS diodes. One protects the 12V other other 5V if you understand how to use a multimeter with the power off you can test the diodes. Many resources on Google for that one. If it shows bad then you can cut it out and see if the drive powers up to recover your data. Don't use the drive like this long term it has no power protection. You can also check for voltage on both sides of the diode with power on "more dangerous" if you are not familiar with the process etc. Keep us posted on your progress

[einstein9]

thnx networks for this

[El Stino]

thx for your replies,

I am familiar with electrics and multimeter, but I'm not very good with electronics, but I do know how to solder.
I used the diode test setting on my multimeter to test forward voltage drop across the diodes.
I also did it on the working board as cross reference.

Across the 12V TVS:
good board: 0.335 forward voltage drop
bad board: 0.000 forward voltage drop

Across the ? diode:
good board: 0.335 forward voltage drop
bad board: 0.000 forward voltage drop

Across the 5V TVS:
good board: 0.832 forward voltage drop
bad board: 1.031 forward voltage drop

Hope you can work with this...
Does this mean the first 2 diodes are broken on the bad board?

Thx again

[networks]

It looks like for sure the 12V diode is bad so cut it. The 12V is what spins the motor as well.

[einstein9]

i recommend to change both 12v & 5v together

good luck

seems ur drive has no problem @ alll

[El Stino]

When you say "cut", what exactly do you mean, just remove it?
Would it be better to replace them with the diodes from the other board?
I don't plan using this drive after I get my data.

[networks]

remove it

[El Stino]

I removed the diodes and the drive is working
Thank you guys!!! Got my pictures back

Ordering Drobo and secondary backup now!

[kingsize]

Hi people! Nice to see some talented people in here

I have followed your advice on cutting out 12v and 5v diodes from a drive like the one mentioned here and I could get my drive to Spin again!!
Before the drive did not even gave a sign of life.

Now the problem is, it starts spinning and it really makes a very normal sound of a perfect running hard drive but in a matter of a 4 or 5 seconds it just shuts down, like if you power it down. I do hear a clicking sound before the "shutdown".

Any ideia on this?

Thanks in advance.

[unknown]

The original problem was TVS, now it's something else.
post the full drive model.

[Good Stones]

Can you see the drive in bios?

[shadowro]

have the similar situation
removed diodes
still nothing

any idea?

motor doesn't spin
not recognized in bios

thank you

hitachi model HDT721075SLA380
p/n 0A38111
s/n MG08JGMA
mlc BA3013