A 29.2 KB PDF documenting the 2SD2639 part, catalogued as a schematic. Nothing beyond the type number is stated in the name. Under the Japanese JIS naming system, 2SD covers NPN bipolar transistors designed for low-frequency use. For repair work the sheet serves to confirm which pin is base, collector and emitter, to read voltage, current and power limits, and to compare candidate equivalents. Check the code printed on the component and the package style on the board before relying on the information.
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.