Reference PDF for the 2SD1197 transistor, 134 KB in size and indexed as a schematic, though the file name is only a part number and reads as a datasheet. A 2SD code under Japanese JIS numbering identifies an NPN bipolar device intended for low-frequency applications. Typical contents are electrical characteristics, curves and the package outline. Before desoldering, use the pinout drawing to identify leads, then check the rated collector-emitter voltage when choosing an equivalent replacement.
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.