Datasheet for the 2SK1923 in a 114 KB PDF, indexed as a schematic. Under JIS numbering the 2SK prefix denotes an N-channel FET, so the file describes one component rather than a board. Use it to find gate, drain and source positions, maximum drain voltage and current, and other parameters needed to judge a substitute after a failure. The file name contains no manufacturer, package or revision information, so compare the marking on the board part with the document before relying on 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.