Short 36.3 KB PDF on the 2SK1803. Part numbers prefixed 2SK are N-channel field-effect transistors in the Japanese JIS registration system, and this file is most likely the datasheet. No manufacturer or package detail appears in the name. A technician uses such a sheet to confirm pinout, read maximum drain-source voltage and current, and judge whether an alternative part can replace a failed one. Compare the original marking and footprint with the document before installing any substitute.
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.