A 180 KB PDF named after the 2SC5255 NPN transistor and catalogued as a schematic, though it is most likely a component datasheet. No device, model or board number is given. Look for absolute maximum ratings, gain classifications, transition frequency and package dimensions with pin numbering. Use it to confirm which pad is base, collector or emitter. Test the junctions out of circuit and make sure any substitute meets or exceeds the original limits.
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)