The 2SA1739 is named in this 44.6 KB PDF, listed among schematics although the JIS 2SA designation shows it is a PNP bipolar transistor datasheet. An _E suffix often marks the English version of a Japanese manufacturer document; nothing else is given. Technicians use it to look up ratings and gain classes, confirm base, collector and emitter positions, and judge whether an available alternative part can replace a damaged one without overstressing 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)