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820-00281 No display. Has external monitor.

bjf

bjf

Member
This came in with very isolated corrosion around the right hall sensor. I repaired that and SMC_LID is at 3.4V but it's still acting like SMC_LID is low. The keyboard is not functional and the screen isn't coming on. It does display on an external monitor though. Not sure what else would be causing this now that I've restored SMC_LID.
 
bjf

bjf

Member
All SMC_LID signals are at 3.4V. It looks like the USBC_TB_CC2 line right next to the lid sensor is missing continuity to CB414. I'm not sure how this would cause this issue but I'll need figure out what's happening there and get a line run.
 
bjf

bjf

Member
Ok, never mind, USBC_TB_CC2 is fine. There is continuity, I just couldn't measure it with DZB551 attached.

Not sure what's happening, why I'm not getting video. This seems like it should have just been a lid sensor issue so I can't imagine it's something deeper. Using a known good screen. I also have another good, identical board here so I'm able to compare numbers. Can't figure it out yet.
 
bjf

bjf

Member
Thanks, yes, that's the only way I do an initial test - just the screen attached. Board sitting on desk with known-good test screen.
 
2informaticos

2informaticos

Administrator
Staff member
You could have two different problems; bad U9850 and bad KB/TP too.
Shouldn't be strange, if liquid affected them.
 
bjf

bjf

Member
So this is actually getting video, but it's running so slow I didn't realize it because it took so long for the video to come up. Online test came back with VDH002 "There may be an issue with a storage device". The only corrosion I could find was near J5260. But something might have hit near U9210 also. I don't see any visible damage though. I can't boot it up so I can't tell if the SSD is recognized.
 
bjf

bjf

Member
Yeah, I always use a USB test drive for testing. If I unplug the lifeboat, it turns on quickly and comes right up with the option-key boot select screen. Once I plug in the lifeboat everything slows down. Either way, I'm not getting beyond the Critical Update screen. I'll never get past it if the SSD is bad. It's one of the reasons this screen comes up. Not sure if this is a problem with the SSD or some components in the SSD circuit.
 
bjf

bjf

Member
Ah, yes, thanks, I forgot about that trick. It will almost certainly boot that way, but what's my next move after that?
 
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