Labelled 2SD1997, this 86.1 KB PDF is indexed as a schematic, yet a bare transistor part number points to a manufacturer datasheet. The JIS 2SD designation identifies an NPN transistor for low-frequency applications such as audio stages, drivers and switching. Use it to confirm the base, collector and emitter pin order and to compare voltage, current and power limits when sourcing a substitute. On the component itself the marking is commonly shortened to D1997, which is worth knowing when reading a scorched part.
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.
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The standard format for schematics, block diagrams, power-sequence charts and service manuals.