HDD: Hitachi Deskstar 250GB SATA 7200rpm 3.5" Desktop PC hard drive HDD P/N 0A36888,
model HDP 725025GLA380
Jan-2008

More info in attached pics

History:
I attached this drive externally to my PC via USB (and external power supply)to get some files. The drive had always worked fine and now would spin up but did not hold its power connection, which I had to jiggle. After a few ons and offs it stopped responding, and I detected a faint hot/burning smell. There were no signs of burning/overheating on the face of the PCB, but sniffing it, there was a definite burnt smell. I detached the board and on the back side, the only chip there was still warm to the touch (unlike the others on the face) and seemed to be the source of the smell. It had a tiny bulge on it, which was easy to scratch off (see picture). Later I tried again, but no sign of life. I have taken no measurements of anything - I would not know what of.
I have since done considerable research about replacing the board and how to find a suitable match, but maybe running some simple tests and/or just replacing that chip would do it?

Thanks for any help and ideas.

The damaged IC is the motor controller. IMO the most expedient solution would be to replace the board and transfer the 8-pin NVRAM chip from patient to donor.

I would test each of the TVS diodes (D3/D4) to determine whether either of them were damaged by an overvoltage. That will tell us something about the nature of the fault.

_________________
A backup a day keeps DR away.

As far as, I'm quite aware of this topic do any one explain about the Hitachi Deskstar so that i can come to somewhat.

Thank you, fzabkar. I understand about the expediency angle, and I will follow that route if I have to.
Meantime, the D4 value = 0.478V/OL and D3 = 0.202V/OL as tested in my multimeter's diode setting.
By the way, the 8-pin NVRAM are both the U5 and U7 chips?

Both of the chips are NonVolatile, so the term "NVRAM" is really a pointless distinction. However, in the Hitachi case the term is mis-used to refer to the microwire EEPROM. AFAICT, U5 is the NVRAM, but I would need to see the part numbers to be certain.

_________________
A backup a day keeps DR away.

The part #s are:
U5 - S93C76 ADVGY 3489
U7 - Pm2SL010 AE0744 M03364C

Do you have a verdict on the diode values? As you can see, everything I do is according to info/instructions I find online, and not all things are that obvious to me. I've read that OL value in reverse bias means a diode is good.

The diodes are OK.

The NVRAM is U5.

Good luck.

_________________
A backup a day keeps DR away.

Once again, thank you very much for your assistance, and best of luck to you too.