820-00281 liquid on keyboard

arnonabuurs

New member
Hello, got this machine it had water liquid spil on the keyboard. The board looks superclean, only one liquid indicator is a little red on the edge of the board, looks like not much hit the board. Even around the liquid indicator that was red all looks clean. I checked voltage, it actually turns on I get 19.5v and then the Amps move up for about 15 seconds from 1.4Amps to 1.55 and then drops to 0v, 19.5v still showing. CPU also gets hot, tried to boot from external drive, light up 15 seconds and then turns off. Any ideas what could cause this? Tomorrow will start measuring all voltages but if anyone has an indication where to look, that would be appreciated.
 

arnonabuurs

New member
Yes, and I also tried with keyboard, display and external SSD connected to see if it can boot but same thing happens, turns on, hot CPU, 19v going up to 1.55A then 19v with 0A, CPU hot

Edit: the display being an external display connected via HDMI, as the original one is just black and I dont have a new one at hand to try
 

arnonabuurs

New member
Here some more measurements:

PPBUS_G3H = 12.58
PP3V3_G3H = 3.418
PPDCIN_G3H_CHGR = 20.08
SMC_BC_ACOK = 3.417
SMC_RESET_L = 3.41
PP3V0_G3H = 3.09
PP3V3_S5 = 3.32
PP5V_S5 = 5.14
PP5V_S4 = 0v
PP3V3_SUS = 3.3v
PP3V3_S4 = 3.3v drops to 0 when Amps drop on meter
PP5S_S4 on U7600 comes up after it gets enable signal, and then drops to 0 with the rest.

SMC bypass didnt work (10 seconds holding powerbutton, keep holding 10 more while charger plugged in, correct me if thats wrong pls)
 

arnonabuurs

New member
Since U7650 did output 5V for a short time i think I can skip that circuit, also no shorts here. Maybe some short in a lower powerline stops it from turning on, will keep measuring my way down and report back if i find more
 

arnonabuurs

New member
OK, seems I have shorts near CPU and GPU... :(. L8000, L7410/20 but also when i measure GPU LA640/650. I guess this is game over :)?
 
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arnonabuurs

New member
I measured CPU temp with my FLircam, it shoots up to 110 Celcius, and then shuts down. Hottest I have seen a mac is 105, 110 seems not good
 

arnonabuurs

New member
Update, after i assembled the mac, i connected the charger one last time (battery disconnected), and fan started to spin, however this time no shutdown and it kept running. I measured voltages around CPU, actually the GPU gets 0.9 volts. CPU GPU was hot but CPU cold while fan was spinning. I get 0v on L7420, would there be a chance that the CPU powersupply failed? Or should i stop wasting my time?
 

arnonabuurs

New member
Yes when i connected the powercable without anything installed (so also no cooling plate) it ran upto 110 degree in 10 seconds. Now I reassembled it it keeps at 0.42 degree same as GPU, fan is spinning hapiilly, but no power to CPU. I did give it another ultrasonic before assembling, wouldnt be the first time some stuff came back to life after that....
 

arnonabuurs

New member
Some more measurements around CPU circuit:

PPBUS_HS_CPU = 12.59 not shorted
PP5V_S0 to U7410/20 = 5V no short
L7330 = 1.12v
L7211/21/31 = 1.09
L7410/L7420 = 0v
 

2informaticos

Administrator
Staff member
You getCPU VCORE, but no iGPU voltage.
I know some old boards don't have iGPU voltage under low graphics charge.
Could be similar thing here.
And if board starts with GPU, no need to power iGPU I think.

Check for USB activity.
 

arnonabuurs

New member

arnonabuurs

New member
Oh i got what you are saying, the integrated graphics is not working when dedicated is turned on, which it seems it is as it gets 0.9v, correct? So this here is not the issue i guess. I also tried to boot from external HDD and although the LED burns its not flickering as it usually does when it boots. It seems the Mac is not booting up, but running.
 

arnonabuurs

New member
But it looks like it is running, cpu is 50 degrees and so is the gpu, and fan keeps spinning. Anyway to make sure of this?
 
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