It is through heads that we can read and write data within hard disks. But long time usage or any impact of uncertain factors (such as wobbling the disk when it is running) might damage the heads, and will lead to long time busy or no response status in ATA mode. At that time, disks can not read the stored data in platters along with malfunctions like incompetence of track seeking, knocking and abnormal sounds, or even no run-up.
In our daily data recovery work, it is frequent to encounter cases with regular bad sectors when doing logical scan, with knocking or abnormal sounds after powering on etc., and we will find the real problem of these cases is the physically damaged head. When heads are physically damaged, data recovery softwares can not get access to stored data, and if we want to get those data, we need to open the disk and replace the corresponding damaged parts and heads.
It is not an easy job to replace the heads. Not only need to be serious, careful, patient, but also a good understanding of disks' internal structure. Frequent disk disassembly to observe and analysis is essential if we want to have a practised head replacement skill. Please noted that, although the working principle of hard disks is nearly the same, but structures are varied with different manufactures. If head parameters between patient and donor are not matched, head replacement can not be done successfully even with top skill. That is to say, a successful head replacement will rely on the suited donor heads to a large extent. So the significance of how to find a suited donor head is self-evident.
In practical head replacement cases, the success rate of Western Digital disks is much higher than what in Seagate disks. Many people feel it is difficult to replace heads of Seagate disks, so in this document, we will focus on the related knowledge concerning to head replacement of Seagate disks, aiming to help all of us to increase the success rate of it.
For details, please refer to http://forum.mrtlab.com/showthread.php?tid=911