Filed as a schematic, this 138 KB PDF bears only the 2SA1204 part number, so it most likely contains the manufacturer datasheet. JIS numbering assigns the 2SA prefix to PNP bipolar transistors. Look here for the absolute maximum ratings, electrical characteristics, hFE ranking and package dimensions. When the part is found shorted, these figures guide the choice of a direct replacement or equivalent, and the pin diagram prevents a reversed fit. Compare the body marking with the sheet before soldering.
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.