The 2SK1826 datasheet in PDF form, sized 320 KB and filed as a schematic. Japanese JIS designations starting with 2SK identify N-channel field-effect transistors. The document should contain limits, characteristics, curves and the outline drawing with pin numbers. It is useful for testing a suspect MOSFET, confirming gate, drain and source, and selecting a replacement with adequate voltage and current margin. Package and marking should be checked on the board first, as the file name states no manufacturer or package.
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.