日本电子维修技术 Hard Drive Repair - PCB（转）
There is a certain amount of agreement, between several of the data recovery service companies, that replacing the PCB, on newer hard disk drives, is a bad idea. In fact, swapping the PCB may actually damage the drive further. They make a good case, have cited examples, and some have gone to great lengths to document their information.
Hard drive customization. At first glance the thought of each and every hard disk drive manufactured being customized, just sounds impractical. Writing variable data to each and every drive? Well apparently they do. If one stops and considers how easy it is and the benefits to the manufacturer's, even the most lay-person will agree.
The variable information is located in some key locations. One such location is the disk itself. There are tracks written to the drive that the average user cannot access. These are known as maintenance tracks. Another location is the EPROM on the PCB. After the mechanical portion of the drive is married to a PCB, during the manufacturing process, the drives are connected to a machine. This machine executes testing, burn-in, writing data to the maintenance tracks and EPROM. Technically, each and every ESDI, SCSI, ATA and SATA drive produced has been customized. The manufacturer's have always stored media defect information in the maintenance tracks. Defects are unique to each drive. So it's not a big stretch to further customize each one. The manufacturer's can reduce their failure rate by tuning the customized information for the thermal and mechanical characteristics of each drive. With the ability to tune each drive made, they can also increase capacity by stabilizing these factors during the manufacturing process.
Consider a serialization scenario. A PCB can be serialized to work with a particular HDA only. That's not too hard. Just write the serial number to the EPROM and the maintenance tracks. During the start-up sequence require the two serial numbers to match. If it doesn't match, it doesn't work.
The future of drive customization is on the horizon. Some reports suggest that the manufacturer's are leaning towards drive level security. The critical information written to the maintenance tracks and the ERPOM, in theory, would be encrypted. That certainly won't make things easier for the board swapper or the data recovery shops.
Is there a "line" where a PCB shouldn't be swapped? The introduction of highly customized information written to hard drives (believe it or not) occurred, to some degree, at the 5MB level (that's 5 megabytes!). With each new generation of disk drive thereafter the customization becomes more intense. In general, the larger the drive the less successful swapping the PCB becomes as a repair solution. The actual destruction factor seems to be limited to particular models at the 20GB level and above. However, I do not have sufficient information to identify them.
I can no longer, in good conscience, recommend swapping PCB's as a repair solution. Do so at your own risk. If you insist on doing so anyway, please use the following guidelines;
For the purpose of hard drive data recovery, the easiest way to get replacement parts and repair your hard drive is to buy another one just like it. Exactly like! Down to the revision!! Including the board!!! That said, the easiest way to repair an electronic problem is to replace the PCB on the drive. There are other electronic components in the drive. But, we'd have to void the warranty and they require special tools to replace. Simply swap the boards from an identical drive? Make sure it's the exact same board! Don't assume it's the same because the model number is the same, or close. Using the wrong board could start a fire!
Swap the boards and see if the symptoms change.
If the symptoms improve to the extent that the drive is recognized by the computer BIOS or SCSI HBA, image the drive now. If the symptoms don't improve, the problem is beyond any help we could provide here. You need professional assistance.
These guides should give you a general idea of what to look for;
[ 本帖最后由 张先生 于 2007-12-9 14:06 编辑 ]
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文章写的太难翻译，不当之处请指正！
硬盘维修--PCB[译文]
在某些数据恢复服务公司之间有着某种协定：在比较新的硬盘上替换PCB是一种不良考虑。事实上交换PCB实际上可能进一步损坏硬盘。他们做了个好的案例（含有引证事例）某些给出了相当长的文件说明他们的信息。
硬盘定制化。粗看起来每一个硬盘厂商定制化的想法似乎是不实际的，难道在每一个硬盘里写不同的数据？但是实际上他们的确这样做的。如果人们静下来考虑一下这是多么容易做到并且对厂商有好处，那么连最外行的人都会同意这样去做。
不同的信息放在某些关键区域。其中这样的区域之一是在盘片上，那里有写到盘片上的普通用户不能访问的磁道，这些磁道被称为服务磁道。另外一个地方是PCB上的EPROM。在制造过程中，当机械部分和PCB装配到一起后硬盘被连接到一个机器上，这个机器执行测试、烧入，把数据写到服务区和EPROM。从技术上来说每一个ESDI、SCSI、ATA和SATA硬盘都是定制的。厂商总是把介质缺陷信息放在侍服磁道上，对于每个硬盘来说缺陷是唯一的。因此进一步定制每个硬盘并不很难。利用对每个硬盘的热和机械特性进行调整厂商可以降低硬盘的废品率。借助稳定那些因素，在制造过程中具有校调每个硬盘的能力还可以增加硬盘的性能。
考虑编号化情景。PCB可以编号为为一个特定的HDA工作并不是很困难，只要把串号写到EPROM和侍服磁道就成。在硬盘启动期间要求两个串号匹配，如果不匹配就不工作。
硬盘定制化的前景已经出现曙光。某些报告显示厂商倾向于硬盘级加密，重要的信息写到侍服磁道和EPROM在理论上说来是被加密的。这些当然对电路板互换和数据恢复商来说更不容易了。
是否存在一“行”，在那里PCB不可以互换？高度定制化的信息写到硬盘（信不信由你）在某种程度上达到5MB级（即5M字节）。对于每个新一代的硬盘定制化因此变得更加厉害。一般说来，硬盘越大换PCB作为维修方式的成功率越低。实际是毁坏因素似乎限定特定型号硬盘于20G及以上，然而我没有充分的信息证明这一点。
清醒地说，我不再推荐换PCB作为一种维修的解决方法，要做的话你自己去冒这个险。如果你坚持要这样做，请使用下面的指引。
为了恢复硬盘数据，最早的方法是买另外一个相象的硬盘获取替换部件并修理你的硬盘，严格相象，包括版本，电路板版本！也就是说最早的修理电子问题的方法是换掉硬盘上的电路板。硬盘里还有另外一个电子元件，我们将失去保修还要有专门的工具去替换。只是从一个一样的硬盘换换电路板？必须确定是严格相同的电路板，型号编号相同或接近。用错电路板等同于玩火！
交换电路板并观察是否症状有改变。
如果症状改进到BIOS或SCSI HBA能够认到，就可以给硬盘做镜像。如果没有进展，问题不是我们这里能提供的帮助所能解决的了。你需要专业人士帮助了。
那些指导应该为你提供了你应该寻求什么的一般思路。
[ 本帖最后由 张先生 于 2007-12-9 19:25 编辑 ]
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Thank Mr. Zhang
So good data both can study and can improve English level
评论
翻译了一下，很辛苦。这个文章本身比较难翻译，似乎写文章的人的写作方式有点与众不同。
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呵呵，外国人说话方式就不一样， 电路 电子 维修 我现在把定影部分拆出来了。想换下滚，因为卡纸。但是我发现灯管挡住了。拆不了。不会拆。论坛里的高手拆解过吗？ 评论 认真看，认真瞧。果然有收 电路 电子 维修 求创维42c08RD电路图 评论 电视的图纸很少见 评论 电视的图纸很少见 评论 创维的图纸你要说 版号，不然无能为力 评论 板号5800-p42ALM-0050 168P-P42CLM-01
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