The 2SD1823 is documented in this 40.5 KB PDF, whose name ends in an unexplained E suffix. Indexed under schematics, it most probably holds datasheet information for an NPN bipolar transistor, as the JIS prefix 2SD indicates a low-frequency NPN device. Technicians read such sheets to confirm pinout and maximum ratings while checking a junction with a multimeter or picking an equivalent. Match the footprint and body marking before relying on it.
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.
Any PDF readerSumatraPDFFirefox / ChromeFlexBV (links PDF to boardview)