Part reference for the 2SC4577, provided as a 106 KB PDF under the schematic type. With the JIS 2SC prefix denoting a high-frequency NPN bipolar transistor, the content is most likely its datasheet; manufacturer and package are not in the name. Repair technicians use such sheets to identify pins, confirm voltage, current and power ratings, and judge substitutes. Check that the package style and marking code on the board agree with the document before soldering in any replacement transistor.
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.