The 2SC5540 transistor is covered by this 30.9 KB PDF, catalogued as a schematic. By JIS convention the 2SC prefix signifies an NPN bipolar device, so the document is most likely a brief manufacturer datasheet. Beyond the part number the name says nothing. Technicians typically use it to identify pin order for in-circuit testing with a multimeter in diode mode and to compare ratings when searching for an equivalent part. Verify that the package shape and marking on the board agree with the drawing.
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.