The only detail in the name is 2SC3450, which under JIS rules identifies an NPN bipolar transistor. This 112 KB PDF is listed as a schematic yet most likely holds the part's datasheet. Technicians reach for such a document to confirm lead identification, voltage and current ceilings and the mechanical outline before replacement. Opens in any PDF reader. Bear in mind the transistor body normally shows C3450 only, and check the package matches the footprint on your board.
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.