Recovery and repair of hard disk HS25YJZ
Hard drives of 1,8" formfactor are quite prevalent in various portable USB hard disks of different producers. They are Verbatim, Transcend StoreJet and some other. These drives undergo mechanical exposure rather badly as any other storage. Considering their tiny size data recovery from such storage is not easy task.
They brought to our Service Centre disk Samsung HS25YJZ 250 Gb for data recovery, rotating velocity of which was 3600 rpm. The disk has been opened before entering our Service; we were not able to figure out why and by whom. When power was on it clicked uniformly and stopped engine. System identified it (because of USB controller) but there was no access to information on the disk.
Failed HDD HS25YJZ
Opened HDD Samsung HS25YJZ
The first step of data recovery from the disk with such symptoms complicated with opening of sealed area in unsuitable conditions obviously is replacement of head assembly for analogical one from donor disk. After this operation drives quite often are not able to operate in normal mode due to instability of positioning system combined with new MHA while adaptive tables are adjust for original heads formed during factory self-test. We should use all available functional of ATA standard for data recovery from such unstable disks.
Moreover, if we try to read information through standard USB, we may face a situation when ATA register has an error (ex. UNC) while bridge continue waiting for data from storage. As a result we have complete crash. Therefore, avoiding of bridge is the first task for files retention. But in case of USB interface performance straightly on bard it is not easy to achieve. In such situations data recovery engineer has to avoid USB bridge and direct connection to PATA-SATA ports.
Chip of USB Bridge JM20335
USB bridge of described disk is on microcontroller JM20335. Unfortunately, signal processor Marvell 88i8038 is assembled on board, it has PATA interface; so four wires will not be enough as in the situation depicted here. It is necessary to solder all 28 signal lines and ground to connect the board to IDE. General operation principle is shown below:
Operation Scheme of USB Bridge JM20335
It is possible to use the schemes below for soldering (from chip datasheet on wison.com.tw):
Crosspatching of JM20335 PATA-USB bridge
Crosspatching of IDE (PATA) interface