PDF of 32.5 KB covering the 2SK656, a part from the JIS 2SK range of N-channel field-effect transistors, so it is effectively a component datasheet rather than a device schematic. The name carries no other detail such as manufacturer or package. Technicians use these sheets to look up pin order, absolute maximum ratings and on-resistance or transconductance values, which matters when diagnosing a shorted part or selecting a replacement. It opens in any common PDF reader on desktop or mobile.
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.