Schematic in PDF form, 1.02 MB, whose name points to MBX-247, a Sony notebook mainboard designation, with an HK1 suffix that likely marks a sub-version or document revision. Sony prints MBX numbers on its laptop motherboards, so that marking should be matched before use. The diagram helps a technician follow power rails, check enable and power-good signals, identify the regulator for a missing voltage and find parts near a short. Open the title block to confirm the exact board and revision covered.
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 @alischematics. 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.