[SOLVED]820-3437 Fucked SMC?

[SMMRepair]

Got a board in that someone had ripped the battery connector off of (or poorly removed it). No damage to the board itself, and I replaced the battery connector and all seemed well. After a few minutes, the fan ramped up and trackpad movement slowed. Ran ASD, and the board failed all kinds of sensor readings tests:

- SMC: 0x0 SMC Critical Sensor Check [FAILED] -- SMC is unable to read sensor
- THSP Thunderbolt Proximity [FAILED] -- SMC is unable to read sensor
- TM0P MLB Top Side [FAILED] -- SMC is unable to read sensor
- TW0P Airport Proximity [FAILED] -- SMC is unable to read sensor
- Tm0P Memory Proximity [FAILED] -- SMC is unable to read sensor
- Ts0P Trackpad Skin [FAILED] -- SMC is unable to read sensor

No liquid anywhere on the board, and none of those appear in the schematics, but the board is clean. Was testing board in my known-good test assembly, but tried it in my 2nd test assembly just in case, and it still fails the same tests. Known-good battery, known-good trackpad, known-good trackpad cable, known-good DC/IO board and known-good DC/IO cable.

Is this a failed SMC? Issues persist even with battery removed, so I don't think it's related to the new battery connected I installed.

All help appreciated, duke.

 

[SMMRepair]

So here's something odd to note, that may help:

The board passes EFI ASD, and the fan doesn't ramp up in EFI ASD either. Fails OS ASD with above noted failures, and fan is full-blast when testing.

 

[dukefawks]

SMBUS for U5810 has an issue. This also goes to the trackpad, check the connector for corrosion also R5390/91. Could also be corrosion under SMC or around U5810.

 

[SMMRepair]

Man, everything looks great. U5810 looks fine, and R5390 and R5391 measure out properly. No corrosion on the connector. I'm thinking of pulling the SMC, but why would the board consistently pass EFI ASD if the SMC was at fault?

 

[dukefawks]

In EFI test the trackpad is in USB mode and in OSX it is in SPI mode. So something between pin 15 and 16 on trackpad connector?

 

[SMMRepair]

Got this one figured out. Removed U5810 to check for corrosion, and it was clean; same issues persisted; pulled SMC to check for any corrosion, it was clean, replaced with known-good, same issues. Touched up trackpad connector just in case it had some funky cracked/bad joint, same issues. Ended up replacing U5810 to be sure, since it was the simplest last-ditch effort, and problem seems to be resolved. Passes ASD.

Thanks again, duke. Another example of a chip that reads well, looks fine, no liquid, diode mode measurements good, but bad. Learned something new with regards to EFI/OS ASD and how information passes through U5810--will be helpful. Solved.

 

[arghhh]

I actually just had a 3437 that was failing all the temperature sensors like that too, and it ended up just being the trackpad flex that was causing all the sensors to fail. I suspect it was causing those SMC data lines to be pulled low.

Cool story bro.

 

[SMMRepair]

Yeah, we have 3-4 known-good test units we use to test our boards, so I was pretty confident it was not related to the trackpad/keyboard/cable, etc. Connector on board looked good and continuity through all pins was fine. I knew it was related to the board itself, either the SMC or the U5810 like duke mentioned. U5810 tricked me because it had correct readings all the way through.