The 2SD968 is covered by this 42.9 KB PDF, whose name includes an _E suffix with no explanation given. Indexed as a schematic, the document concerns an NPN low-frequency bipolar transistor according to the Japanese JIS 2SD scheme. Open it with any PDF viewer for pin configuration, absolute maximum ratings and electrical characteristics. Use the data to test the removed part with a meter, confirm it has failed, and select a replacement of matching polarity, package and equal or better ratings.
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.