LG D690 service manual in English, labelled version 0.9 and dated 140822 in the name, which reads as 22 August 2014. At 44.0 MB it is a large PDF that usually combines schematics, component placement and troubleshooting flowcharts. Technicians use such manuals to trace power rails, find test points, follow disassembly steps and identify spare part references. As a 0.9 release it may be a preliminary edition, so confirm details against the board. Open it with any PDF reader that handles large files.
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 @c_f_s. 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.