The 2SA1709 is documented in this 154 KB PDF, which the index lists as a schematic though its name contains only the part number. Under the JIS scheme, 2SA parts are PNP bipolar transistors, so the content is most likely a datasheet with limits, characteristics and package dimensions. Before trusting a substitute, compare collector-emitter voltage, collector current, dissipation and gain, and verify lead order on the actual case, as similarly named neighbouring part numbers can differ in package and pinout.
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.