Tagged as a schematic, this 28.3 KB PDF bears the JIS designation 2SK3449 and is best regarded as the datasheet for that component. In Japanese numbering, 2SK covers N-channel field-effect transistors. Open it in any PDF reader to look up the pinout, package drawing and absolute maximum ratings needed for diagnosis and replacement. Read the marking on the original part carefully, since prefixes are often omitted on the body, and confirm footprint and pin order before fitting a substitute 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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The standard format for schematics, block diagrams, power-sequence charts and service manuals.