Very small 22.2 KB PDF relating to the 2SD1999, filed as a schematic. The name offers nothing but the part code, which follows the JIS scheme where 2SD denotes an NPN bipolar transistor for low-frequency or power use. Given the size, expect a brief sheet with core ratings and perhaps a pinout. That is enough to identify leads and sanity-check a replacement. Confirm the marking on the component, typically abbreviated D1999, before using it during a repair.
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.
Any PDF readerSumatraPDFFirefox / ChromeFlexBV (links PDF to boardview)