Samsung HD400LD - remove TVS

[marvin42]

Hi!

I'd like to ask your advice.

The power supply (12 V and 5 V) was swapped on my Samsung 400 GB PATA HDD.

After that it does not spin up any more.

I've bought a similar PCB (same model number/serial on both PCBs - BF41-00106A, rev 08, Trident), replaced them and now the HDD spins up, gives a knocking (?) sound, then powers down after 2-3 sec.

I've searched and read through this forum, and found that removing the +5V TVS _may_ help.

I've also read that since +5V rail got +12V, the preamp may be dead as well. In this case, the new PCB should die as well.
Fortunately, it survived, still working with its original HDD.

I've compared both PCBs with a multimeter in diode mode (first I separated the PCB form the HDD).

I've found that 5V TVS is short (No 1. on the picture).
Also, I've also found that parts numbered 2-5 are also short, which are not on the donor PCB.


My questions are:
- is it safe to only remove TVS (No.1), or shall are replace the other parts as well?
- actually, what are those parts marked No. 2...5?

Thanks,

marvin

Attachments

Samsung HD400LD PCB - parts marked red are short

[SAjunky]

Too many broken parts to be true. These parts are likely capacitors. Most probably they are in parallel with TVS and are short by TVS. Remove TVS, test it, to make sure what happened, then re-test remaining parts.

[marvin42]

Dear SAjunky,

it was a good reasoning, yes, that was the case: I've removed the TVS and after that none of the others are short!

Now as I understand, if I put back the PCB onto the original HDD, if the preamp is OK, then it should work normal, right?

Please assure me

[ici_lemmy]

then it should work normal, right?

Right, it should.

[marvin42]

I can't believe it, it works!!!

This forum rocks!

In the past days I've read through many posts and learnt a lot!

This HDD was dead for many years, I just found it again on a remote shelf (waited for some money for DR), and now, I am backing it up!!!

A big thank all of you!


For those who has similar problem: before you try other PCB, check TVS first with a multimeter in diode mode.
If you are lucky, the preamp is fine, and then it's enough to remove TVS.
Please search the forum for TVS for throughout information.
I've bought a PCB, swapping did not work for me (each PCB contains special info about its HDD; firmware, bad sectors, etc).
In addition, as I learnt, a dead preamp could kill the new PCB as well.

[loki]

Congratulations Glad it worked.

I had a Samsung on Saturday that had the wrong PSU connected.
A quick test using the continuity test showed that the 12v was shorted to the ground.
Also the 5v TVS was faulty. Fitted new TVS diodes & got all the data back, customer will be happy & price is less than they were expecting

Loki

[SAjunky]

In the past days I've read through many posts and learnt a lot!

Ccongratulation!

Now if you are going to use this drive, don't store anything important here - for the first few months. And don't forget to glue in a good replacement