Reference PDF, 218 KB, for the 2SD2584 component, indexed under schematics. In Japanese JIS numbering, 2SD indicates an NPN bipolar transistor designed for low-frequency applications, so the document is most likely a datasheet. The file name gives only the part number, with no manufacturer, package or revision. Technicians rely on such sheets to identify leads before diode-mode testing, read breakdown and current limits, and confirm a candidate substitute matches or exceeds the original ratings.
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.