Covering the 2sk2580, this 34.5 KB PDF is labelled a schematic yet identifies only a semiconductor part, pointing to a short datasheet. The 2SK prefix follows the Japanese JIS convention for N-channel FETs. Expect a pin diagram, package outline and core ratings in a page or two. Technicians use such sheets to locate gate, drain and source quickly, test for shorts and choose a substitute with at least equal voltage and current capability. Verify the case style and marking 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.