PDF reference, 105 KB, for the 2SK1813 transistor. In the Japanese JIS scheme, 2SK designates an N-channel field-effect transistor, so this is probably its datasheet. The file name carries only the part number, without maker, package or revision. The sheet typically defines absolute maximum ratings, electrical characteristics and pin assignment. Use it to identify terminals during diagnosis and to qualify a replacement. Confirm that the footprint and printed marking on the board match before relying on the data.
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.