PDF reference for the 2SD1852, a 2SD-series NPN bipolar transistor, about 96.5 KB and more likely a component datasheet than a circuit diagram. Check collector-emitter voltage, collector current, power dissipation and hFE ranges when choosing an equivalent, and use the package drawing to identify the pins. A diode test across the junctions shows whether the original part is open or shorted. Compare the case marking against the document before substituting, since lead order can vary between manufacturers.
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.