820-00165 missing PM_SLP_S4_L

[jadao]

This one has no liquid, is clean and just died one day on its own. Customer powered it off and it never powered on again.

I 've checked all these signals for PM_SL_S4_L and they are present.
PPVRTC_G3H
RTC_RESET_L
PCH_SRTCRST_L
PCH_INTVRMEN
PCH_DSWVRMEN
PCH_CLK32K_RTCX1
PP3V3_S5
PM_DSW_PWRGD
PP3V3_SUS
PM_BATLOW_L
PM_RSMRST_L
PM_PWRBTN_L

When I plug magsafe CPU_VCORE apears or pulses briefly twice and stay at 0V after. Same thing with ALL_SYS_PWRGD and SMC_DELAYED_PWRGD.
If I trigger SMC_ONOFF_L, CPU_VCORE will pulse only once.
If I do an smc bypass, I see the fan spins twice and stop

Is there any hope I can check something else or most likely a PCH issue? Especially that i have no liquid damage...
Thanks

 

[2informaticos]

Pulsing twice, is the worst repair scenario for this board.

Check if all voltages on pages 11 & 58 try to appear too.
For tests, start first in SMC bypass, then trigger SMC_ONOFF_L for voltage checkings.
This gives you a bit more time to catch the pulses.

I recovered several boards heating CPU/PCH with quality flux.
Should insist more on PCH area.

 

[jadao]

Thanks for the tip, it works very well with smc bypass and a wire soldered on SMC_ONOFF_L.
All voltages on pages 11 and 58 try to appear, I noted the values below.

I tried heating PCH with flux but didn't change anything...

Page 11
PP3V3_S5=3.3V
PP3V3_SUS=3.3V
PP3V3_S0= Pulses to 3.3V and goes back to 0,099V
PP1V5_S0SW_AUDIO_HDA= pulses to 1.5V and goes back to 0V
PP1V05_S0=pulses to 1.05V also at R1280-pin2, L1275-pin2 and L1270-pin2 and goes back to 0.005V
PP1V05_S0SW_PCH_HSIO=pulses to 1.05v also at L1290-Pin2 and L1295-pin2 and goes back to 0.005V

Page 58
PP1V5_S0= pulses to 1.5V and goes back to 0V
PP3V3_S4=Pulses to 3.3V and goes back to 0,34V
PP3V3_S3=Pulses to 3.3V and goes back to 0,48V
PP3V3_S0_FET_R=Pulses to 3.3V and goes back to 0,099V
PP3V3_S4SW_SNS=Pulses to 3.3V and goes back to 0V
PP5V_S0= pulses to 5v and goes back to 0V
PP3V3_S0SW_SSD_FET_R=Pulses to 3.3V and goes back to 0V

 

[2informaticos]

Check all SPI Bus Termination resistors and their traces.
Be sure J6100 is clean.
Just in case, you may try known good BIOS.

Check resistance between pins 17/18 and 27/28 of U7100.
Also check the sensor circuits from pages 41-43.

You can also try ultrasonic cleaner.