820-3115 slow, asd error TA0P

[Yoel Ren]

this macbook came in alive, but cursor is staggering, and macbook is slow, fan maximum,
i run asd 3s155 os version, and see that TA0P ambient air sensor is failed
smc have greenish thing near it, and i already reballed smc but still the same, i can't seem to locate ambient air sensor location..

 

[2informaticos]

Try known good trackpad board/flex.

 

[Yoel Ren]

trackpad and the cable surely good..,other board works flawlessly on that cable and trackpad

 

[2informaticos]

Inspect trackpad connector.
Test the board disconnecting webcam and airport.

 

[Yoel Ren]

trackpad connector looks good
the backside of trackpad connector near u5805 has a bit of greenish thing.. but im not sure where's the wrong unless i measure something.

 

[Yoel Ren]

disconnecting webcam airport still same
u4850 doesnt look too good, but does it matter ?

 

[2informaticos]

I cannot find U4850 on 3115 schematic.

 

[Yoel Ren]

sry I mean u4580..

 

[piernov]

TA0P should be Q5510. Only failing sensor? (make sure to select continue on error in ASD)

 

[2informaticos]

Inspect U5510 area for corrosion.
Check continuity to its sensors, Q5510/15/20.
Be sure parallel caps are not corroded.

 

[Yoel Ren]

yeah ta0p is the only failing sensor, and some memory test too
i have replaced q5510 and q5520, but still the same..
board is relatively clean off corrosion..

 

[Yoel Ren]

parallel caps is not corroded

 

[2informaticos]

Heat PCH with quality flux.

 

[piernov]

Did you check continuity as instructed?

 

[Yoel Ren]

yeah continuity is good, all sensor is connected to each other and to u5511's caps too.
heat pch but still the same, time to let it go then..
thanks for the guidance piernov and 2informaticos!

 

[2informaticos]

I've got similar problem on 2936 board.
In that case, two series resistors are placed on PCH SMLink 1 (R5222/23).
I solved the problem removing these resistors.

For 3115, PCH SMLink1 is directly connected to PCH.
Try to cutoff these lines, close to PCH.

 

[grmacs]

I had same issue with a 3115 except all three thermal sensors were intermittently flagging errors in ASD and fans were running high. Reheat of U5511 and reball of SMC fixed the issue. In my case all 3 sensors had good continuity to connections on the board and were reading similar voltages/pulses.