Covering the 2SA1905, this 213 KB PDF is listed under schematics, yet the name gives only the component code, so it most likely contains the datasheet. Japanese JIS designations that start with 2SA belong to PNP bipolar transistors. Technicians consult such sheets for terminal assignments, absolute maximum ratings and gain grade letters. When choosing a substitute, compare voltage, current, power and frequency figures, and confirm the package pin layout, since equivalents in the same case do not always share pin order.
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.