820-3437 possible sensor fail

PCTRONICS

New member
Gday guys I have an 820-3437 board that was liquid damaged and would not turn on and had corrosion all around LP8550, short on LCD connecter. after these few components were replaced I now get a chime and it now boots into OSX. the problem I'm having is the fan stays on high after about 1 minute and everything is loading very slow. could someone please assist me with a link to 3s156 as I'm having trouble locating the file. any assistance would be gratefully appreciated.
 

PCTRONICS

New member
Thanks mate, i changed to a good trackpad flex. this is not the issue but thanks for the file. its coming up with sensor issues in ASD so ill start looking around sensor voltage divider etc. any further assistance would be appreciated.
 

2informaticos

Moderator
Staff member
VP0R is PBUS sensor.
Poste exact voltage for PPBUS_G3H and SMC_PBUS_VSENSE:
Check for corrosion around Q5500.

Finstack sensor is on LIO board.
Try known good LIO board/flex.
Also check for corrosion at J9500.
 
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PCTRONICS

New member
PPBUS_G3H 8.56v
SMC_PBUS_VSENSE 0.166v
Q5500 looks clean
i have many IO boards so will swap out
J9500 is clean, all pins are in tact and solid.
 

2informaticos

Moderator
Staff member
First, use new post to reply; the comments are not easy visible if the thread will go ahead in more pages.

"SMC_PBUS_VSENSE 0.166v"
That's no good; should be aprox 2.5V for 60W charger.
Post Q5500 voltages.
 

PCTRONICS

New member
ive been using a lab PSU for many years now. i always set it to 18.5v
Q5500 P1 GND@0v P2 3.43v P3 8.53v P4 8.54v P5 Fluccuates between 3.42 & 3.5v P6 0v

Thank You.
 

PCTRONICS

New member
Mate this machine almost owned me. are you saying SMC_PBUS_VSENSE 0.166v is correct?

i already checked R5503/04 and C5504 last night and they were correct. im sorry to be a fucktard but i put the IO flex under the scope and there was a cockroach pube inside it. i swapped the IO board out as well and done another ASD scan and it came back clear. from a logical point of view i guess this would be correct though. Im installing High Sierra now and will report back if this job is done. Thank you so much mate. now i have another 9 similar boards to look at.
 

PCTRONICS

New member
it appears that pubic hairs from cockroaches can cause a 820-3437 to run like shit. this job is done thanks.
 
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