Small 67.8 KB PDF for the 2SD1854, a part number in the Japanese 2SD series of NPN bipolar transistors, so it is really a datasheet rather than a full schematic. Use it to check pinout, package, maximum voltage and current ratings, and gain before fitting a replacement. It also helps you test the part with a meter: compare base-emitter and base-collector junctions with the ratings listed. Confirm the device marking on the case, as suffixes can change the package or gain class.
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.