The 2sd2394 NPN transistor is covered by this 53.3 KB PDF, which the index files as a schematic. JIS part coding uses 2SD for low-frequency NPN bipolar types, so the file is a device datasheet. It should list absolute maximum ratings, current gain classes and the package outline, though the name itself gives no further detail. Use it when diagnosing output, driver or regulator stages built around this part, and match the case marking before ordering a replacement.
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.