A 359 KB PDF named for the 2SC2498, a transistor designated under the JIS scheme, where 2SC identifies NPN devices. The schematic label in the index aside, the file most likely holds the manufacturer's datasheet. It is handy when diagnosing a shorted or open transistor, because the ratings and pinout tell you how to test it with a meter in diode mode. Compare the package and any hFE rank letter on the original before replacing 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.
Any PDF readerSumatraPDFFirefox / ChromeFlexBV (links PDF to boardview)