A schematic diagram for Dell hardware (board 13040-1). Shared as “13040-1_Vostro_3900_3800_3902元件位置图.pdf” — a .pdf file, 342 KB.
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 @ShareMan_Electronic_Files. 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.