Package for the Apple logic board 820-3330 at revision B, stored as a 3.59 MB ZIP archive. The name does not list what is inside, though files of this size commonly hold a schematic and sometimes a matching boardview. Revision letters on Apple 820 boards can mean component and layout changes, so compare the PCB silkscreen carefully. Use the drawings to trace power rails, check the SMC and charging circuits, find test points and narrow down the component behind a short.
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 @cyberlanelectonik. Enginerys does not host this file.
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Compressed archive that every operating system opens without extra software.
Built-in OS tools7-Zip