Small 58.3 KB PDF titled 2sc5103 in lower case, catalogued as a schematic yet evidently a short datasheet for the 2SC5103. The 2SC prefix in Japanese JIS numbering marks an NPN bipolar transistor, normally stamped C5103 on the body. Even a brief sheet like this usually gives pinout, package outline and maximum ratings, enough to identify the leads on the board, verify the part with a meter and compare candidate substitutes for voltage, current and power capability.
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.