Covering the 2SK443, this 95.2 KB PDF sits under schematics, though the JIS 2SK naming for N-channel field-effect transistors indicates a component datasheet. It probably contains package drawings, pin assignments, rating limits and characteristic curves. Use it to orient the part correctly on the board, check for drain-source or gate shorts, and find a replacement with equal or better voltage and current figures. The name gives nothing else, so match the actual marking first; any PDF viewer will open 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.