Component datasheet in PDF form, 57.8 KB, for the 2SD1478, though the index files it under schematics. The 2SD prefix is Japanese JIS coding for an NPN bipolar transistor of the low-frequency class, and the E suffix in the name is unexplained. The sheet should cover ratings, electrical characteristics and the package outline. A repairer uses it to locate the base, collector and emitter pins, check the part with a meter and judge replacements before soldering one in.
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.