A 164 KB PDF dedicated to the 2SD1221, recorded as a schematic in the catalogue. Japanese JIS numbering uses the 2SD prefix for NPN bipolar transistors in low-frequency applications. Expect a specification sheet with maximum ratings, DC characteristics, hFE classes and an outline drawing showing pin positions. Before installing a replacement, match the case style and lead sequence to the original, and when no exact part is stocked, compare voltage, current and dissipation figures to pick a safe equivalent.
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.