Apple schematic collection archive of about 784 MB, the first of a numbered brand series. The name does not say which MacBook or other models or which 820-series board numbers are included. Apple logic boards are identified by an 820-xxxxx number printed on the PCB, and that number is the reliable way to choose the right schematic. Technicians use these diagrams to follow power rails, check PPBUS and standby voltages and trace signals when diagnosing a dead board."}
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 @videocard_notebook_resistance. 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.