Transistor datasheet for the 2SD2155, stored as a 177 KB PDF and filed with schematics. The 2SD prefix follows the Japanese JIS numbering, which designates an NPN device intended for low-frequency use. Repair technicians open a sheet like this to confirm pin order, package outline, collector voltage and current ratings and gain before replacing a failed transistor or cross-referencing an equivalent. Always verify base, collector and emitter positions against the drawing, since pinouts vary between packages.
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.