Persian-language PDF of 377 KB whose title translates roughly as Western hard drive repair, indexed as a schematic. No specific drive model, PCB number or controller is stated in the name, so open it to see which Western Digital boards it covers. Such guides typically help with checking TVS diodes and the motor driver, measuring supply rails on the drive PCB and swapping the adaptive ROM chip when moving to a donor board. Match the donor board number exactly before relying on its advice.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @generalproblemsolved. Enginerys does not host this file.
How to open a .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.