A 105 KB PDF for the 2SJ421, catalogued as a schematic but in practice a component datasheet, since the 2SJ prefix in the Japanese JIS numbering system marks a P-channel field-effect transistor. The name gives no maker, package or revision. Technicians open such a sheet in any PDF reader to confirm pinout, drain-source voltage, current rating and on-resistance before fitting a replacement or a substitute. Check the package marking on the board against the document, because similar numbers can come in different cases.
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.