Apple schematic in PDF form for logic board 820-02536, size 4.06 MB. The name carries only the board number, no Mac model, so identify the machine by the 820 number printed on the logic board itself. Apple's 820-xxxxx codes uniquely identify each logic board design. The schematic lets you follow power rails, check the expected voltages, trace signals between chips and understand the power-on sequence when a board will not charge or boot. A matching boardview with the same number helps locate the parts.
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 @boardviews_schematics. 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.