RAR archive with a PDF schematic for the AMD variant of the N61B board, as the name states, sized at 2.54 MB. No revision number is included. The diagrams serve for tracing power rails from the adapter input through to the AMD processor and chipset supplies, identifying component values and following signals between connectors and controllers. Unpack it with WinRAR or 7-Zip and view in any PDF reader. Since Intel and AMD versions of a model differ substantially, make sure your board is the AMD build before use.
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 .rar file
Compressed archive — the usual wrapper for a schematic + boardview pair or a BIOS + EC set.