WD7500AAKS ROM recovery

The WD7500AAKS hard drive, according to the customer, had been idle for about 10 years. Examining the printed circuit board (PCB), a poor soldering condition was observed. The solder mask is greyish and brittle. ATA registers do not respond. The first thing that catches attention is the absence of the ROM chip (see image U12). For this disk, the ROM is located in the microchip of the controller. Usually, in such cases, a donor electronic board is used by transferring the customer's ROM to the donor board. To avoid soldering, as heat can cause unforeseen damage, the ROM is usually read using the Tx Rx serial communication port. In this case, as well, it would be the only way to obtain the ROM content. But the customer's board is damaged and ROM can't be read out.

While waiting for the donor board to arrive, I decided to attempt to repair the customer's board by restoring the soldering on the controller contacts. Signs of life appeared in the ATA registers, but the controller heated up significantly. This is where the repair also ended.

Upon the arrival of the donor PCB, the work could continue. The customer's disk was connected to the donor electronic board, with which it is possible to work with the disk's service area (SA). There is one crucial nuance here. Any PCB board will not work because its ROM contains configuration data. If the given configuration does not provide servo marker reading, then working with the SA will not be possible. To increase compatibility, a very close donor disk needs to be found. Alternatively, an attempt should be made to re-sold the controller.

In this case, a donor disk was purchased (the manufacturing date differs by a month) with a faulty motor. The PCB board from this donor turned out to be compatible enough to read SA tracks and extract the necessary modules. Then, I tried another board with the same board number but obtained without a disk. It was not possible to access the SA tracks.