Only the part number 2SD2088 appears in the name of this 171 KB PDF, so treat it as the datasheet for that transistor. JIS rules reserve 2SD for NPN bipolar transistors intended for low-frequency service. Repair use centres on confirming lead assignment, maximum collector-emitter voltage, collector current and dissipation, plus the gain bins if a suffix appears on the case. Any PDF viewer opens it. Check the package outline against the part removed from the board before you order a substitute.
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.