PDF sheet for the 2SC3935 part, with an _E suffix after the number, filed under schematics at 40.7 KB. Under the Japanese JIS scheme the 2SC prefix marks an NPN transistor, usually a high-frequency type, so this is almost certainly a component datasheet rather than a board diagram. Technicians open it in any PDF reader to check pinout, package outline, maximum ratings and marking codes before fitting a substitute. Confirm the body marking matches before you rely on the pin assignment.
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.