A 34 KB PDF linked to the 2SK2123, listed as a schematic but probably the device's datasheet. The 2SK prefix identifies an N-channel field-effect transistor in the Japanese JIS registry. No manufacturer, package or revision appears in the name. Open it in any PDF viewer to read the pinout, ratings and characteristic data. Compare the part marking on the board first, since closely numbered 2SK212x devices can differ in voltage and current ratings.
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.
Any PDF readerSumatraPDFFirefox / ChromeFlexBV (links PDF to boardview)