We got a really weird one in the shop last week and I've just been trying to figure out exactly what could cause the issue's we're experiencing. The symptoms are odd:
820-00923, no liquid, no damage, not previously-repaired, etc.
1. Unit powers up and boots fine; passes AHT, SSDs wipe/install OS perfectly fine, unit will run for hours under stress, and charge/discharge totally fine from ALL four ports. No issues until...
2. You try to boot to an external drive (OS installer or bootable drive, doesn't matter) using ONLY the "bottom" port on each side of the unit. Board boots perfectly fine to external drives on both "top" ports--both orientations; no issues. Issue only occurs on each "bottom" port--both cable orientations. When you try to boot to external using the bottom ports, roughly 30% into the loading progress bar, the board throws the prohibitory sign (circle/line through it). The behavior is *exactly* the same, every single time.
3. Also, to add to the strangeness, the unit does detect USB devices and drives in the problematic ports just fine, so the power supply for the CD3215s seem fine (typically we would not see any USB device detected when those fail), but to be sure, I replaced them anyway--same problem.
4. Performed clean install, new BIOS, etc., same issue.
5. Issue exactly the same across 3 different test-cases with 3 sets of USB-C port assemblies, etc.
Every single time I've EVER encountered the prohibitory sign, it's always ended up being a no-fix (PCH was consensus on several occassions). But, those boards typically had much more significant failures accompanying the sign. In this case, I'm hopeful we "may" find the issue/cause because the boards works so well in every other way. We've combed over the entire board several times and found zero damage.
Really stumped on this one! Hoping we aren't looking at a PCH or CPU issue. Curious to hear any thoughts!
820-00923, no liquid, no damage, not previously-repaired, etc.
1. Unit powers up and boots fine; passes AHT, SSDs wipe/install OS perfectly fine, unit will run for hours under stress, and charge/discharge totally fine from ALL four ports. No issues until...
2. You try to boot to an external drive (OS installer or bootable drive, doesn't matter) using ONLY the "bottom" port on each side of the unit. Board boots perfectly fine to external drives on both "top" ports--both orientations; no issues. Issue only occurs on each "bottom" port--both cable orientations. When you try to boot to external using the bottom ports, roughly 30% into the loading progress bar, the board throws the prohibitory sign (circle/line through it). The behavior is *exactly* the same, every single time.
3. Also, to add to the strangeness, the unit does detect USB devices and drives in the problematic ports just fine, so the power supply for the CD3215s seem fine (typically we would not see any USB device detected when those fail), but to be sure, I replaced them anyway--same problem.
4. Performed clean install, new BIOS, etc., same issue.
5. Issue exactly the same across 3 different test-cases with 3 sets of USB-C port assemblies, etc.
Every single time I've EVER encountered the prohibitory sign, it's always ended up being a no-fix (PCH was consensus on several occassions). But, those boards typically had much more significant failures accompanying the sign. In this case, I'm hopeful we "may" find the issue/cause because the boards works so well in every other way. We've combed over the entire board several times and found zero damage.
Really stumped on this one! Hoping we aren't looking at a PCH or CPU issue. Curious to hear any thoughts!
Comment