The 2SK2129, a JIS-registered N-channel FET, is the only thing the name identifies in this 32 KB PDF. It is filed as a schematic but is most likely the component datasheet. The maker and package are not stated. Repair use is simple: confirm pin assignment before measuring for a drain-source short, read the voltage and current limits, and check that any substitute matches or exceeds them. Neighbouring 2SK212x files in the index cover the related part numbers.
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)