Part 2SK1438 is the subject of this 108 KB PDF, filed in the index as a schematic but almost certainly a component datasheet. Under the Japanese JIS naming system the 2SK prefix marks an N-channel field-effect transistor. The name gives no maker, package or ratings, so read those from the document. Technicians use such a sheet to confirm pinout, voltage and current limits and on-resistance before fitting a substitute. Compare the marking on the device itself before relying on 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.