At 214 KB, this PDF named 2SC4118 is filed as a schematic but is most plausibly a fuller datasheet for that part, likely with characteristic curves. The JIS 2SC prefix denotes an NPN bipolar transistor, typically marked C4118 on its package. Use it to identify terminals, check voltage, current and dissipation limits and compare gain or frequency behaviour when sourcing an equivalent for a failed stage. Since the name omits manufacturer, revision and grade, verify the marking and suffix on the original part before relying on it.
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.