Part documentation for the 2SC4855, supplied as a 122 KB PDF in the schematic section. The name provides no model or board details. In Japanese JIS/JEITA numbering the 2SC prefix stands for an NPN bipolar transistor, so the file should be a datasheet covering ratings, characteristics and dimensions. During repair it assists with identifying the fitted part, confirming pinout before measurement, and selecting a substitute whose voltage, current and power ratings equal or exceed the original.
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.