The 2SK2598 is documented in this 418 KB PDF, listed among schematics but named only by part number, which indicates a component datasheet. JIS nomenclature uses 2SK for N-channel FETs. Expect pin assignment, package outline and electrical characteristics such as breakdown voltage and drain current. These figures are what a technician needs when a switching transistor reads shorted and a suitable equivalent must be found. Compare body marking and package to the drawing before treating it as the correct device.
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.
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