The 2SA1539 part number gives this 41.0 KB PDF its name, and although it is filed under schematics it almost certainly holds the datasheet for that transistor. In JIS numbering, 2SA identifies a PNP device for high-frequency circuits. When a board shows a shorted or open transistor, the datasheet tells you which leg is base, collector and emitter and what ratings a substitute must meet. Compare the body marking and package with the drawing inside before ordering or soldering a part.
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.