820-00840 Waterdamage

Inwerp

New member
minor waterdamage in Backlight Area, nothing special. Signs of fluid in Camera connector, no corrosion, cleaned, resoldered.
Backlight Ok(removed corrosion+ replaced U8400),
chimes, boots, 100% Fan/AHT: PFM006, NDC001, PPN001

PFM006 and PPN00 = temp sensor, NBC001 = Camera, nothing really suspicious: IO activity, camera 5V present.
can someone advise where to seek sensors on this board? does it have sensor on audio board?
 

JohnB8812

New member
Run HWMonitor and see which sensors are failing. Also, try the board in a known working housing if possible.
 

Inwerp

New member
unfortunately i have no display assembly to test. if it was older board it could be SMC SDL SCL shorted to ground but this board has only one chip on this line for CPU Thermal sense + Camera. I hope its not The Camera because than it will really suck.
I will check with HWMonitor, device boots needs like 20 min to boot.
 

JohnB8812

New member
If the camera on the screen is the issue, it SHOULD boot normally and not have errors without the screen attached can confirm that
 

Inwerp

New member
with display connected i got 128C on all sensors except CPU/Gpu internal and "incoming air" . Also, Camera can be disconected separately (small cable left to the USB C side), makes no difference.
also i have 1/2 Sec pulses on Airport Temp sensor (the only one i can measure in chassey)
without Display all sensors except SSD Temp and Airport are OK, pulse is the same, 1M to ground.
with SSD removed 128C are on Mainboard Proximity and Airport.
is it okay for temp sensor to pulse voltage?
I still hope this is mainboard side problem since i still have failed sensors without the display assembly. U5870 is a good candidate to check, but CPU sensors are OK.
Theres nothing funny on SMC line either, just bursts of signals.
 

Inwerp

New member
so if someone looks for a sollution without replacing crappy flexgate display.
remove R8556 R8558 to cut failed sensor from the SMC communication line.
camera works, no idea if something else will not work(i guess some crappy light sensor should be definetely dead, who cares), would not recommend to update system since Apple is Apple.

Please mark as "solved"
 

2informaticos

Administrator
Staff member
This way, you've disconnected ALS sensor, which is connected on the SMC SMBus 1 with various temperature sensors.
ALS sensor is placed together with iSight camera, but its SCL/SDA lines are independent.

Your problem was definitely ALS sensor; not worth to change it.
 

Inwerp

New member
I wonder why it fails so funny, i mean it does not really pull down the smbus, it just posts some trash so line wont be recognized by smc anymore. I mean i do not see any difference on oscilloscope, but it definetely fucks up the whole line. Afaik it fails pretty often in the exact same way. Good job apple for putting some non-critical light sensor on the line which is used for the temp meter IC.
 
Last edited:
Top