2013 13" MacBook Air Fans running full speed. ASD Errors 820-3437-B

wrbailey

New member
Machine turns on and chimes and will boot to desktop. Charges, etc... just fine.

This machine has the fans running full speed.

I've run ASD and I get these sensor errors:

TA0P -- Input Air Flow (ERROR - Sensor is reading below the limit)
TC0P -- CPU Proximity (ERROR - Sensor is reading below the limit)
THCP -- Charger Proximity (ERROR - Sensor is reading below the limit)
TS2P -- S2 Camera Proximity (ERROR - Sensor is reading below the limit)

This board did have minor liquid damage.

Is there a certain area of the board I should be focusing my efforts on?

Thank You!
 

wrbailey

New member
I was looking around the schematic and found that U5800 has to do with the "CPU Proximity, Inlet ,DDR and BMON THR Sensor"
I do have 3.3v at PIN 1 (VDD), however I am not sure what other readings I should show, or what exactly would signify a fault or a bad reading...
 

dukefawks

Administrator
Problem with data bus SMBUS_SMC_1_S0. Disconnect camera first and see if errors are gone. Check camera connector for corrosion. Measure diode mode on both data lines.
 

wrbailey

New member
Had tried disconnecting camera last night. Still had errors remain. I will check SMBUS_SMC_1_S0 this evening.
 

wrbailey

New member
Like I said without camera plugged in, still errors.

Checked for 3v at R5360/R5361 and its 3.3v and diode mode on pin2 of both is: 0.542/0.538
Both resistors measure about 1.98k
 

dukefawks

Administrator
Then it could be bad U5800/corrosion in camera connector/corrosion under SMC. Check GND on pin 6 of U5800 first though.
 

wrbailey

New member
What would PIN6 indicate? I do have 0V at pin 6. So that is correct, right, 0ohm resistor to ground. What does it show at PIN6 when it is not correct? So I will swap out U5800, as i see no corrosion/liquid damage by the SMC, I'll report back I guess
 

wrbailey

New member
the u5800 IC is still soldered/welded to the board. I'm guessing that is a definite sign that it is part of the issue. I'm afraid to put too much heat on the chip, as it sits opposite of the CPU. Any recommendations? Heat the hell out of it to get it off and then cross fingers it didn't kill the CPU??
 

wrbailey

New member
Replaced the U5800. Still giving exact same errors... any ideas? Didn't screw up CPU. Still boots, chimes, everything. Just loud fans after a few moments.
 

dukefawks

Administrator
Data bus issue then. Anything connected to SMBUS_SMC_1_S0_SDA can cause this. Usual suspects would be corrosion under SMC/camera connector/U5620. But any component on these lines can cause an issue.
 

wrbailey

New member
DING DING DING!!! U5620 was the issue. Didn't have to remove it. Heated with flux and scrubbed and then cleaned with alcohol and "ESD" safe haha q-tips and no more loud fan and passes all ASD.

Thanks again for your help and wisdom! Makes me wonder why U5800 was so SOLDERED onto the board!?!?
 

wrbailey

New member
So I made the ultimate STUPID mistake and put a slightly longer screw back into the fan top left screw hole. Now I get a screaming fan as soon as I press the POWER button. Any way to repair this, or did I just screw myself. I want to curl up into a little ball. I'm so pissed that I made that mistake. Apple does this on purpose, I swear...
 
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wrbailey

New member
That screw stand-off for the fan exactly on the opposite site of the U5620 and the screw did go into the board, are we sure that wouldn't screw stuff up?
 

wrbailey

New member
I'll run ASD again.

However my previous comment about ASD passing was prior to completely reassembling it and causing the screw hole damage. The fan was working as it should, nice and quiet, UNTIL I put the longer screw in the wrong hole, while assembling it. I'll try a different fan when I get back home, but I am not holding my breath. The stand off is exactly opposite of U5620. I'm sure it'll fail ASD now.
 
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