missing pm_slp_s4_L 820-3476

[shanenin]

I am working through a missing pm_slp_s4_L on an 820-3476. The board appears clean.

here are the following readings
PPVRTC_G3H : 3.3v
PM_SYSRST_L :1.9v LOW?
PM_PCH_PWROK: MISSING
PM_RSMRST_L: 3.3v
PM_PWRBTN_L: 3.3v
SMC_ADAPTER_EN: 3.3v
PM_BATLOW_L: 3.3v

One of the issues seems to be PM_SYSRST_L is only 1.9v. That line is powered by PP3V3_S0, which is also 1.9v.
I am missing my P3V3S0_EN to turn on u8030 which produces my needed PP3V3_S0.
To produce P3V3S0_EN I need PM_SLP_S3_L which is 0v. Now I am unsure where that gets produced or maybe my logic is just way off on this whole path I am following. Thanks for any help. Shane

edit added later//
I did replace u8030, along with u1900, u1950

 

[2informaticos]

You cannot pursuit PM_SLP_S3_L before getting PM_SLP_S4_L.

Trigger SMC_ONOFF_L and check for drop pulse at PM_PWRBTN_L (at same time).

 

[shanenin]

You cannot pursuit PM_SLP_S3_L before getting PM_SLP_S4_L.

Trigger SMC_ONOFF_L and check for drop pulse at PM_PWRBTN_L (at same time).

Thanks. I am assuming trigger must mean short to ground. Can I check for a drop pulse by just holding a voltage meter on PM_PWRBTN_L?

can I ask another question? how come I have 1.9volts on pp3v3_s0? Is that even possible without PM_SLP_S4_L?

 

[2informaticos]

"I am assuming trigger must mean short to ground."
More information available here:

HOW TO collection

I hope this "How to" collection will help our members. I will possibly modify this post in time, if updates available. Trigger SMC_ONOFF_L (PMU_ONOFF_L): It reffers to simulate power button function, when the keyboard is not connected. We need to do this when we work with the board...

boards.rossmanngroup.com

"how come I have 1.9volts on pp3v3_s0?"
Don't waste time with that...

Do not quote an entire post, visible few centimeters above.
Write directly into Reply box, instead of clicking Reply button.
Please, mainatain forum aesthetic.

 

[shanenin]

Trigger SMC_ONOFF_L and check for drop pulse at PM_PWRBTN_L (at same time).

when I trigger SMC_ONOFF_L PM_PWRBTN_L drops fromm 3.4 volts to .3volts

May I ask what this is helping us figure out?

 

[2informaticos]

It means that SMC correctly sends out to PCH the power button signal.
Now check if PM_SLP_S4_L pulses at same time.

 

[shanenin]

Now check if PM_SLP_S4_L pulses at same time.

when I trigger smc_onoff_L while checking voltage of pm_slp_s4_L it stays at 0v. What is this checking for?

 

[2informaticos]

Means that PCH doesn't properly react.

Check PM_DSW_PWRGD, PCH_DSWVRMEN and the 4 RTC signals.

 

[shanenin]

Check PM_DSW_PWRGD, PCH_DSWVRMEN and the 4 RTC signals.

3.4 and 3.2 for the first two. I am not sure what 4 signals you are referring to. I am guessing this is to do with u1900 (I did swap it prior).

I am getting 32.7khz on pin 12 of u1900

 

[2informaticos]

"I am not sure what 4 signals you are referring to"
Read this...

HOW TO collection

I hope this "How to" collection will help our members. I will possibly modify this post in time, if updates available. Trigger SMC_ONOFF_L (PMU_ONOFF_L): It reffers to simulate power button function, when the keyboard is not connected. We need to do this when we work with the board...

boards.rossmanngroup.com

 

[shanenin]

the 4 RTC signals.

just curious, if we have 32.7 khz, does the imply we have all of these signals? Asking to try and understand

 

[2informaticos]

NO!
Didn't read that thread yet???

 

[shanenin]

Didn't read that thread yet???

I did , but maybe read it wrong

 

[2informaticos]

RTC clock (32KHz) is provided externally to PCH.
It has internal RTC clock generator, but Apple doesn't use it...