820-3115 fan speed one turn and off

raainxx

Member
Hi,
i have this board liquid spill near SMC. I put the board in a ultra sonic cleaner, now i clean but can start, just fan and stop.
i change the SMC, U7000 (because PPBUS_G3H is low 12,26, now 12,57). i try the board with original charger 85W.
I have the all_SYS_PWGD=3,34V just few seconds and fall when fan stop.
U7000 17/18=3ohm and 27/28=20ohm
do you have any idea, where i can find the problem?
thanks
 

2informaticos

Administrator
Staff member
Check R7402/03 as first step.
Do you get voltage on all big coils (pulse at least)?
Try to start in SMC bypass, still turns off?
 

acowan

Member
I'm working on a similar problem.

Does the fan start smoothly or do you have a stutter?
Is the fan spinning at full speed - loud
 

raainxx

Member
R7402 = 150K
R7403=182K
L7330 = 1,5V and fall
L7260 = 5V and fall
L7220 = 3V3 always
L7630 = 1V and fall
L7100 =1V and fall
L7550 = nothing
L7510 = nothing
L7520 = nothing
SMC Bypass not work, same problem turn fan normally and shutdown
 

2informaticos

Administrator
Staff member
"L7510 = nothing
L7520 = nothing"
Nor even pulsing?

Also check for pulse (at least) at pin 4 of U2650/60.
 

2informaticos

Administrator
Staff member
Monitor all voltages on pages 71/72.
Check for short all them.

Did you solder another SMC pulled from 3115 board?
 

raainxx

Member
I check all voltage on page 71/72, all pulse at the good voltage but after fall, some voltage don't fall at 0v.
No short find on this voltage.
Yes i keep the smc on other same board 3115.
 

raainxx

Member
i check all SPI resistors seems all good and trace too.
I check with scope all the signals on U6100, all signal communicate but not on pin 3 & 7. is it normal?
i change the bios with good bios same problem and i clean me of the original with cmizapper same.
 

2informaticos

Administrator
Staff member
Check all voltages from pages 71/72; any pulse at least?
Also check for short all them.

Test the board alone, nothing connected, only charger...
 
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