PDF schematic named only Ramsés, with no device type, brand or board number given, so its contents can only be confirmed by opening it. The size of about 1 MB suggests several pages or scanned drawings. The collection it sits in is mostly audio amplifiers, so it may be an amplifier or audio project, though the name does not confirm this. Once identified, use it to trace supply rails, follow the signal path and locate parts for fault finding. Check every value against the components fitted to the real board.
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 @pdf_servicemanual. 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.