820-2476 Freezes, unable to replicate, all ASD tests passed but components missing

[Jay]

As the title suggests, this Mac works fine. It's been on the bench for days running all kinds of tests and it just keeps purring along. ASD162 fails only 1 test which is the Thermal Interface TIM test but I hear this test always fails in ASD162 even on a brand new Mac so this can be ignored.

I opened it up to see if there was any damage on the board anyway and found a clean board with nothing visually wrong.

When comparing to the boardview and schematic though, there are quite a few components missing. They are not listed on the schematic as "NO STUFF" or "OMIT" so to my understanding, these should be present on the board.

One of these missing components may be the cause of the "computer freezes" the client reported but without being able to experience the issue first hand... what can one do?

Is there a common fault on/with these boards that I should look in to just in case?

 

[dukefawks]

I very much doubt it is stuff missing from the board. There are many things the are not listed as NO STUFF that will still not be populated.
Locking up could be pretty much anything and if narrowed down to the board is usually a no fix on 3476 boards unless it is corrosion somewhere.

 

[Jay]

Thanks for the reply dukefawks.
Is there a repository of high res images for known good logic boards I can visually compare with in the future? If there’s basically no way for me to tell if a component should be there or not from the board view and schematics, known good boards are all that’s left to compare with correct?

No corrosion and I’ve been over the main board and io board a few times. This will be a no-fix like you said.

Would you be willing to check out the “missing” parts and confirm they are indeed not part of the final design? If so, I’ll list them when I get back to my office.

 

[dukefawks]

Googling the board number should get you enough pictures to compare. But don't waste your time, it will not be the issue. Probably bad RAM or the machine was exposed to an impact.

I assume you removed SSD and booted from USB and disconnected IO board to make sure it is the board. Also verified with external keyboard that it is not just the keyboard/trackpad.

 

[Jay]

Thanks dukefawks. I did none of those things as I can't replicate the problem to begin with. With that and no visible issues, this is a no-fix. Appreciate your time!