Apple logic board schematic for 820-3115, revision B, provided as a PDF. The 820- prefix is Apple's own part numbering for logic boards, and the name does not state the Mac model, so identify it from the number printed on the board. The schematic shows power rails, the SMC, charging circuits and the power-up sequence, which helps diagnose no-power and shorted-rail faults. Use it with the matching 820-3115 boardview, and confirm the board number and revision 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 @cidschematicandboardviewofficial. 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.