pm_slp_s4_L missing 820-00165

[shanenin]

I have a board with no obvious signs of water damage. Part of me thinks it may have been cleaned at another shop. I am not getting my s4 rails to come on. Here is what I know

I am using a genuine 85 watt charger

I have these rails present
8.6 ppbus
3.42 pp3v42
3.3 pp3v3_s5
5.0 pp5v_s5


I have some but not all of the following signals which I have been told are important for s4 states
0.0 PM_SYSRST_L
0.0 PM_PCH_PWROK

3.3 PM_RSMRST_L
3.4 PM_PWRBTN_L
3.4 SMC_ADAPTER_EN
3.3 PM_BATLOW_L

I have tested u1900 with an oscilloscope and do have a clock signal

u1950 looks perfect and I have power to it, but no output
3.42v on pin 8
I do NOT have any voltage at pm_pch_pwrok


I have no corrosion around the bios chip and the test points look good

the issue seems to be at u1950, but don't understand what enables it

 

[2informaticos]

Trigger SMC_ONOFF_L signal and check if PM_PWRBTN_L drops to 0V at same moment.
It should come back to 3V when SMC_ONOFF_L is released.
If it reacts, then check if PM_SLP_S4_L pulses at least in that moment.

Be aware of wrong assumptions; these are S0 signals...
"I have some but not all of the following signals which I have been told are important for s4 states
0.0 PM_SYSRST_L
0.0 PM_PCH_PWRO"

 

[shanenin]

Thanks 2informaticos!

how would I trigger SMC_onoff_L?

So I understand the bigger picture, Is u1950 needed for s4 power state? I thought, maybe incorrectly, it was, but if its main signal outputs are for an s0 state that does not seem to be the case.

 

[2informaticos]

"how would I trigger SMC_onoff_L?"
Solder a wire at SMC_ONOFF_L line and touch the ground with it; R5115/16 pads can be used.

U1950 has ALL_SYS_PWRGD as main input; which appears in S0 state, just before the VCORE.

 

[shanenin]

when I trigger smc_onoff_L it does cut the power to pm_pwrbtl_L and it also causes a pulse on pm_slp_s4_L when looking on the oscilloscope. What does this mean? Just trying to understand

 

[2informaticos]

Check for pulse on all big coils.
If PM_SLP_S4_L pulse, all S3 volatges must pulse too.
PM_SLP_S3_L should also pulse, check that.
If yes, S0 voltages must pulse at least.
Check if ALL_SYS_PWRGD pulses too.
Is better to use o-scope to catch any fast pulse.

 

[shanenin]

Check for pulse on all big coils.
If PM_SLP_S4_L pulse, all S3 volatges must pulse too.
PM_SLP_S3_L should also pulse, check that.
If yes, S0 voltages must pulse at least.
Check if ALL_SYS_PWRGD pulses too
Is better to use o-scope to catch any fast pulse.

just curious. what are we trying to figure out?

edit added later//
I wonder if I somehow made things worse. Now pm_pwrbtn_L is 0 volts. I am also no longer getting any pulsing on pm_slp_s4_L when shorting smc_onoff_L

edit added later//
now I noticed the green light is off and my ppbus just dropped to 8.1v

I wonder if I shorted something or I have a wire soldered to smc_onoff_l and maybe it hit something it should not have(just a signal with low amperage)?

On a positive note, this was my board and no real harm done.

 

[2informaticos]

Do not tied SMC_ONOFF_L to ground; just touch the ground for an instance, like pressing power button...

 

[shanenin]

Do not tied SMC_ONOFF_L to ground; just touch the ground for an instance, like pressing power button...

I only attached a wire to smc_onoff_l then tapped the other side of the wire to ground when I wanted to trigger it. Something else is keeping the smc off :-{

 

[shanenin]

My smc_reser_L has voltage. Does that implie the smc may be bad since I only have 8.1 volts on ppbus_g3h?

 

[2informaticos]

SMC_RESET_L is OK, as you have correct PPBUS_G3H and Magsafe light even.
Unelss the actual situation is different; please confirm.
"now I noticed the green light is off and my ppbus just dropped to 8.1v"

PM_PWRBTN_L should go back to high level, when SMC_ONOFF_L is released.

BTW, do NOT quote an entire post from few cm above; is not aesthetic...

 

[shanenin]

1. something changed, my ppbus is now just 8.1 and I have no light
2. I no longer have PM_PWRBTN_L voltage (probably related to the smc not turning on)

 

[2informaticos]

Recheck all the points you tocuhed before PPBUS_G3H went down.
Do you get 3V at SMC_RESET_L?
If not, solve that...

 

[shanenin]

I am getting 3.4 at smc_reset_L is that normal?

 

[2informaticos]

Yeah, is correct.
Posta again all the signal value...