Datasheet for the 2SA879 in a 49.9 KB PDF; the trailing _E in the name probably denotes an English version, though the name does not confirm it. The 2SA prefix, part of Japanese JIS numbering, identifies a PNP bipolar transistor, and no product or board model is mentioned. Pages of this size usually hold a ratings table, key characteristics and outline drawing. Use it to verify pin order and limits when servicing older equipment, and confirm any modern equivalent shares polarity, package and sufficient voltage margin.
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.