Schematic & Boardview files for 820-00431-A

[mon2]

Anyone have the schematic & boardview files for A1418 iMAC 820-00431-A?

Many thanks if you can share or can suggest a similar logic board.

[SMDFlea]

Re: Schematic & Boardview files for 820-00431-A

from logiwiki https://logi.wiki/index.php/Schemati...s_Availability

820-00431 ❌ ❌ Some sections near I/O ports vaguely similar with 820-3588.

[mon2]

Re: Schematic & Boardview files for 820-00431-A

Thanks. Have that info already but unfortunately does not help on the case.

Trying to decipher the non-documented PCB straps that define the soldered 178 ball BGA devices on the iMAC (A1418 820-00431-A) logic board.

Specifically, there are RAMCFG0..RMCFG3 = 4 straps.

Each can be made to be HIGH or LOW.

Wish to confirm their exact position on the logic board and respectively decode how the LPDDR3 memory vendor is selected (ie. SkHYNIX vs. SAMSUNG).

Fairly sure that we have decoded 8GB vs. 16GB strap and now SkHYNIX vs. SAMSUNG strap.

The youtube video from iBOFF is very nice and a must watch for the procedure. Amazing that they located some of the straps but the information is not complete.

They started with SkHYNIX 8GB (1866 Mhz) and changed a single jumper to upgrade to SkHYNIX 16GB (1866 Mhz). Yet, according to their own chart (if we understand correctly), 2 jumper changes must be made so a bit confused.

We will experiment with a known good logic board to see if we can 'crack' this puzzle.

Attached is a pic of a known good 16GB A1418 820-00431-A with SAMSUNG LPDDR3 supplied by Apple.

This information is rare so perhaps later on, once we are confident, will post onto the logiwiki for future readers.

Appreciate your help.