Part reference for the 2SC4686, provided as a 223 KB PDF and indexed as a schematic. The number follows the Japanese JIS convention in which 2SC marks an NPN bipolar transistor, so the contents should be its datasheet. The name provides nothing more. Typical uses include identifying pins in the package, checking breakdown and current limits, and evaluating cross-reference parts. Match the body marking and package on the circuit board before relying on the pinout drawn here.
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.