Boardview for the Apple MacBook Pro 13-inch A1278 with logic board 820-3115-B, the B revision of this board, in a 152 KB ZIP archive. Apple's 820-xxxx numbers identify the logic board itself, and several boards share the A1278 model, so check the number etched on the PCB. Open the file with OpenBoardView, FlexBV or a similar viewer to locate components and test points, trace power rails such as PPBUS and follow signals while chasing shorts or missing voltages.
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 @cynetitsolution. Enginerys does not host this file.
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