Indexed as a schematic, this PDF is named 2SD1459, a Japanese JIS designation that points to a datasheet for an NPN transistor rather than a board diagram. The 2SD prefix marks NPN parts intended for low-frequency use such as audio, switching and power stages. At 122 KB it opens in any PDF reader. Technicians use such sheets to confirm pinout, maximum voltage and current ratings and package before fitting a replacement. The body is often marked only D1459, so check the full marking and package against the document.
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 @cyberlanelectonik. 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.