Tiny 30.2 KB PDF named 2sk65, a JIS part number that indicates a component datasheet, although it is filed as a schematic. In that scheme 2SK refers to an N-channel field-effect transistor. Use it to identify pins and read maximum ratings before replacing a suspect device or picking a modern equivalent, which is common for older part numbers. Because the file is small, expect limited data; verify package and pinout physically, and handle the replacement FET with antistatic care.
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.