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820-3662 Slow with adapter, stuck on drive-select screen, boots normally with battery

bjf

bjf

Member
Somewhat of a cluster, this computer looks like a lot of people have worked on it. It came in with the usual assortment of incorrect screws and destroyed connectors. I'm assuming it was originally liquid-damaged. It will boot normally with the battery connected, but without it, it will never get past the drive-select screen. Everything is extremely slow after you hold down Option to get to the drive-select screen. You can keep selecting the drive and the arrow with respond to clicking it but it will never move past this screen (at least after letting it sit for an hour.)

I think it actually is booting (activity on external drive light) but it's the slowest boot speed possible. It would probably take all day to get there. But on battery, this will all work normally, boots into external or internal drive. EFI ASD is not giving any errors. I'm booting from an external test drive.

So in the end, this is basically a slow-on-adapter-only issue. Extremely slow.
 
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bjf

bjf

Member
Yes, checked them and all are good. PPBUS is at a stable 12.6V. This came to us with a garbage fake battery so I'm still thinking you're on the right path. No visible damage on the board that I can find so it may not be a spill after all. I'm going to keep looking at the ISL circuit for clues.
 
bjf

bjf

Member
Replaced ISL. No change. Check R5441 and continuity with traces and all are good. Not sure what's left besides the SMC.
 
bjf

bjf

Member
Thanks, yeah, that's the path I was on. Everything measured fine and this area wasn't hit by liquid but I just replaced all 6 of the sense resistors and the ISL and the error went away. EFI ASD has no errors now. OS version has a few PCI errors (SATA, Thunderbolt, Bluetooth).
 
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