Reference PDF for the 2SD1453 transistor, catalogued as a schematic though the name points to a part datasheet. The 2SD prefix identifies an NPN bipolar device under the Japanese numbering system; nothing else is stated in the file name. Open it in any PDF viewer to read collector-emitter voltage, current and dissipation limits, plus the package drawing, so the correct leads are identified and a suitable equivalent can be chosen when the original part has failed.
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.