Large 24.8 MB PDF schematic for the MHC-V83D, a high-power home audio system model name used by Sony, though no brand is given in the file data. The size suggests a full service manual with several boards covered. Technicians use it to trace the switching power supply, standby and protection circuits, amplifier stages, disc and USB sections and lighting control. Open it in a PDF reader with search to jump to part references, and check the board numbers on the actual PCBs match the drawings.
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 @datasheets1. 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.