A 106 KB PDF named only 2SC4459, placed in the schematic category of the index. That JIS-style code marks an NPN bipolar transistor designed for high-frequency operation, so the file is best approached as a parts datasheet. Read it to confirm package outline, terminal arrangement and limiting values before fitting a replacement. Diode-mode readings of the junctions taken with a multimeter can be compared against the device structure described, and the case marking should be verified against this part number.
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.