Hello everybody and thanks for your help in advance. I have an WD4000AAKS, external hdd. When i plug in in, the hard drive starts humming for 4-5 times, no spinning, but no clicking noise either. After it's stops and starts again. I observe that the Smooth L7251 2.2 chip it's getting extremely hot. I suppose that should be faulty. There's no visible burn damage on chip. Can anyone help with some advice pls? If somebody has a replacement board, I'd like to try change the boards, to see if that will fix my problem. My board doesn't have the U12 chip, so i will need someone to upload the firmware from the old board to the new one.
Thank you very much for your time.
The specs on the hdd are:
WD4000AAKS
S/N ; WMASY0655831
MDL : WD4000AAKS - 00A7B0
PRODUCT OF MALAYSIA
DATE 30 MAR 2008
DCM EBRNHV2CA
R/N 701537
LBA 781422768
400.0 GB
WWN: 50014EE0AB3AF137
THE BOARD NO
2061-701537-E00 02P XW 5N09 URRU 6 0003370 8373

Most possibly this is stiction problem. I have seen this a couple of times being caused by PCB, but it's very rare.

If problem is stiction, not a DIY i'm afraid (if you care about data).

If PCB and since there is no U12 on the pcb, you can ask a pro company to do it for you (it WON'T be that costly).

Better yet, have a pro evaluate this drive and quote you for recovery. Some pro's offer free evaluation so you know what you're dealing with, and what it'd cost to have data back.

Good luck.

_________________
http://www.northwind.gr
SandForce SSD Recovery
Ransomware Reverse Engineering - NoMoreRansom! partners

A simple test to check if it's PCB related is to find a board and swap it, and check what happens.
But as northwind said, I also do not think it's PCB related, and you should take care on how many times you start the drive, because that could cause more harm to it.

Probably you can at least find a company that make free diagnosis to be able to check what's the issue.