Archive for Apple logic board 820-00923, 2.28 MB in RAR format; the name gives only the board number, so contents could be a schematic, boardview or firmware and must be checked after extraction. The 820-xxxxx numbering is Apple own scheme for logic boards and identifies the exact PCB rather than the Mac model. Technicians use such material to trace power rails, locate components and diagnose shorts, or to rewrite the EFI flash. Verify the 820 number etched on the board before relying on any of 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 @schematicslaptop. 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.