A 43.6 KB PDF tied to the 2SD1820, including an E suffix that the name does not explain. The catalogue treats it as a schematic, yet a transistor part number like this almost always points to a datasheet. In JIS numbering, 2SD identifies an NPN bipolar transistor for low-frequency service. Use it to read the pinout, hFE ranks and voltage and current limits when testing or replacing the device, and compare the case outline with the PCB pads.
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)