820-00165 not turining on

[iClub]

Good morning this mac suffered oxidation in the region U1950,Q8150 and U8160, I replaced it, but it won't turn on.


Voltage:

PPbus 8,59V
PP3v42 3v42
all_SYS 0V, pulses to 3V
PLT_RST 0V.
PM_DSW_PWRGD 3,4
PCH_DSWVRMEN 3,24V
SMC_ADAPTER_EN 3,4V
PM_BATLOW_L 3,3V
PCH_CLK32K_RTCX 0,428V
V PCH_INTRUDER_L 3.065V
V_SRST_L 3,3V
PCH_INTVRMEN 3.24
RTC_RESET_L 3.33V

 

[2informaticos]

What about pins 7 & 3 of U1950?
Check for pulse at least.

Q8150 is redundant protection, not really needed.
Many times I just remove it from the board...

 

[iClub]

7 - 0V, pulsing 3V.
3 - 0V, pulsing 2,3V

 

[2informaticos]

Keep in mind, your borad tries to turn on, as you get pulsing voltages.
Not booting is what we need to find why.

Do you get pulse on all big coils, including PCH and CPU?

 

[iClub]

Voltage / diode mode
L3095 0V, no pulse / 0.530
L7130 8.58V / 0.148
L7520 0V, pulses 5V / 0.435
L7560 3.34v / 0.370
L7430 0V, pulses 1.179V / 0.175
L7630 0V, pulses 1.026V / 0.217
L7310/20 0V, pulses 1.527V / 0.016

 

[2informaticos]

Any pulse at PLT_RESET_L?
I bet something more affected for corrosion.

Did you try SMC bypass mode?

 

[iClub]

Any pulse at PLT_RESET_L?

PLT_RESET_L 0v, pulses 2.5V;

When you trigger the SMC bypass the cooler turns and stops.

 

[2informaticos]

Check all SPI Bus Series Termination resistors and their traces.
I recommend to reball SMC.
There may also be accumulated crap underneath CPU; you should heat it with quality flux.

Sometime, BIOS corruption can occur on corroded boards.