Here the 2SK3285 is documented in a 48.6 KB PDF, placed in the index's schematic section. A 2SK number identifies an N-channel FET in the Japanese JEITA scheme, usually a MOSFET for switching duty. With this sheet a technician can map the terminals, check drain-source voltage and current capability, and compare the package with the footprint on the board. Before ordering a replacement, confirm the device marking and make sure the substitute meets or exceeds the listed 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.