Schematic for the Apple A1278 13-inch MacBook Pro with logic board 820-2530, carrying the K24 project code. Apple prints its 820-xxxx board number on the PCB, and since A1278 spans several board generations, that number must match before you rely on these pages. The PDF lets a technician follow PP-named power rails, check the SMC and power sequencing, locate fuses and test points and trace shorted lines from the MagSafe input onward. It opens in any standard PDF reader with searchable signal names.
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 @hrtechno. 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.