Catalogued as a schematic, this 100 KB PDF is named after the 2SC4031 and is most likely its datasheet. JIS numbering uses 2SC for NPN bipolar transistors. Maker, package and ratings are not mentioned in the name and must be read from the document. Typical repair uses include identifying base, collector and emitter before diode-mode testing, confirming maximum voltage and current, and comparing an equivalent part. Open it with any PDF reader and check the part marking on the board before ordering a replacement.
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.