Boardview for the Apple logic board 820-2532, supplied as a RAR archive of 1.10 MB. Apple identifies its boards with 820-xxxx part numbers silkscreened on the PCB, and that number is the reliable way to match a file to a machine. After extracting, open the board file in a viewer such as OpenBoardView, FlexBV or a similar tool to search parts, highlight nets and find test points while chasing shorts or missing rails. Pair it with the matching schematic when possible, and verify the 820 number first.
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 @alischematics. 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.