PDF schematic titled Tin Yat 80A, which appears to be a project or platform code name rather than a retail model; the name gives no brand, board number or revision. At 1.16 MB it is likely a full motherboard drawing set. Use it to trace power rails, follow signal paths and locate components and test points during board-level repair. Since the identity is unclear, check the title blocks inside the document and match them against the board number printed on your PCB before using it.
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 @schematicslaptop. 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.