Datasheet-style PDF, 379 KB, for the 2SK1486 N-channel FET, going by the Japanese 2SK type prefix in the file name. The catalogue tags it as a schematic, yet nothing in the name points to a particular appliance or board. Repair work typically draws on such a document for the pinout, gate threshold, on-resistance and safe operating limits, which matter when checking a suspected failed transistor or choosing a substitute with equal or better ratings. A normal PDF reader is all that is needed to view it.
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.