820-00165-A Missing PP5V_S4RS3 and PP3V3_S4SW_SNS

[Flippers McCoy]

Re: 820-00165-A Missing PP5V_S4RS3 and PP3V3_S4SW_SNS

None taken! I definitely agree, a heat gun is far from ideal, and it's likely preventing me from doing as good a job as I could. Honestly I wouldn't be too broken up if I didn't get the job, I very much enjoy repairing motherboards

[piernov]

Re: 820-00165-A Missing PP5V_S4RS3 and PP3V3_S4SW_SNS

If PP3V3_S4 is there that would be great news, make sure you have PM_SLP_S4_L.

[Flippers McCoy]

Re: 820-00165-A Missing PP5V_S4RS3 and PP3V3_S4SW_SNS

PM_SLP_S4_L doesn't exist, still
On a hunch, I checked for continuity to ground on PM_SLP_S4_L, and it's shorted to ground!
It's a 3.3V rail, right? So I should start by injecting voltage into the rail and see what gets hot

[Flippers McCoy]

Re: 820-00165-A Missing PP5V_S4RS3 and PP3V3_S4SW_SNS

So I started trying to figure out where the short on PM_SLP_S4_L is, and I learned that it is only shorted to ground when the board has the adapter plugged in.
Is it safe to inject 3V to find a short, or is that even necessary?

[SMDFlea]

Re: 820-00165-A Missing PP5V_S4RS3 and PP3V3_S4SW_SNS

Have a look at the power state table, page 59 on the schematic. Test everything on the PM_SLP_S4_L rail U3510 ,

[Flippers McCoy]

Re: 820-00165-A Missing PP5V_S4RS3 and PP3V3_S4SW_SNS

To confirm I'm interpreting the table correctly, the 1s mean that state is off/inactive, and 0s mean that that state is on/active, right? So the rails on the top of the table are necessary in order to have all the 0s below them.

All the components passed a visual inspection, but I don't think that really counts for much at this point. I didn't bother checking to see if the ICs were outputting what they're supposed to because they both operate on S3 or S4 rails, and we're not even getting into S4 state.

R1461: 49 Ohms
U3510: 48 Ohms
U4810 (pin 1): 52 Ohms
U4810 (pin 5): 50.5 Ohms
R8179: 50.5 Ohms
R8111: 49.5 Ohms
R8116: 50 Ohms
R8112: 51 Ohms
R8117: 52 Ohms

[SMDFlea]

Re: 820-00165-A Missing PP5V_S4RS3 and PP3V3_S4SW_SNS

The 1 = enable

[Flippers McCoy]

Re: 820-00165-A Missing PP5V_S4RS3 and PP3V3_S4SW_SNS

Ah, so the opposite of what I thought then, good to know
I think I see what you were getting at, PM_SLP_S5_L is in the exact same boat as PM_SLP_S4_L with a short to ground only when the adapter is plugged in.

The only component that I can see that both these rails have in common is the CPU, and I would be loathe to think the CPU is at fault here

[SMDFlea]

Re: 820-00165-A Missing PP5V_S4RS3 and PP3V3_S4SW_SNS

I could be wrong here,but the only things i can see in common are 2 resistors R1460 (100K ohms) and R1461 (100K Ohms) , and U8170 Pin 2 PM_SLP_S5_L to U8170 Pin 4 S4_PWR_EN that goes to,amongst other things Q2090 Pin 2 S4_PWR_EN to Q2090 Pin 5 PM_SLP_S4_L

[Flippers McCoy]

Re: 820-00165-A Missing PP5V_S4RS3 and PP3V3_S4SW_SNS

Both Q2090 and U8170 don't exist, they seemsto be part of a diagnostic circuit for test boards. It looks like literally the only things that are real that PM_SLP_S5_L actually goes to are U5000, R1460, R8115, and U0500. I would try removing R1460 and R8115 one by one to see if either removes the short, but I don't see how either of them being shorted would cause these symptoms specifically

[Flippers McCoy]

Re: 820-00165-A Missing PP5V_S4RS3 and PP3V3_S4SW_SNS

Okay, so I discovered that all three of these rails are shorted to ground:

PM_SLP_S5_L
PM_SLP_S4_L
PM_SLP_S3_L

Perhaps a bad SMC?
None of the other resistors in that area of page 13 are having problems like this

[SMDFlea]

Re: 820-00165-A Missing PP5V_S4RS3 and PP3V3_S4SW_SNS

Both Q2090 and U8170 don't exist, they seemsto be part of a diagnostic circuit for test boards. It looks like literally the only things that are real that PM_SLP_S5_L actually goes to are U5000, R1460, R8115, and U0500. I would try removing R1460 and R8115 one by one to see if either removes the short, but I don't see how either of them being shorted would cause these symptoms specifically

Damn these apple schematics, i must have been zoomed in too far to see (For development only)

[SMDFlea]

Re: 820-00165-A Missing PP5V_S4RS3 and PP3V3_S4SW_SNS

It could be a bad SMC, it might just need reballing. You`ll need to reball an SMC sooner or later .

[Flippers McCoy]

Re: 820-00165-A Missing PP5V_S4RS3 and PP3V3_S4SW_SNS

If it's the SMC I'll have to set it aside for another day.
I did a little more research, and it looks like in order to get PM_SLP_S4_L, you need PCH_PWROK, and to have PCH_PWROK you need PM_S0_PGOOD. That comes from U1950 on page 17. I checked on it and it has power coming in on pin 8, but pins 1 and 2 are both 0V, so it's not creating PM_S0_PGOOD. I looked into where ALL_SYS_PWRGD and CPUVR_PGOOD_R come from, but I quickly got lost.
I used this Rossmann video to learn more about this circuit
It looks like the whole short to ground thing was a misdirection and may be supposed to happen? Apparently testing for continuity while power is on a board is a no-no.

[piernov]

Re: 820-00165-A Missing PP5V_S4RS3 and PP3V3_S4SW_SNS

You need to have the AC adapter *unplugged* to check for shorts.

PM_SLP_S4_L doesn't need PCH_PWROK AFAIK. The power ok signal would be RSMRST# in this case.

[Flippers McCoy]

Re: 820-00165-A Missing PP5V_S4RS3 and PP3V3_S4SW_SNS

You need to have the AC adapter *unplugged* to check for shorts.

That's what I thought, but I never saw it put explicitly like that, thank you

PM_RSMRST_L is 3.29V. Is that supposed to be low in order to get PM_SLP_S4_L?
I also get 3.33V on pin 2 of U8130 and 3.29V-3.3V on pin 4

PS: How can I tell which power ok signal is for which rail?

[piernov]

Re: 820-00165-A Missing PP5V_S4RS3 and PP3V3_S4SW_SNS

No, RSMRST# is supposed to be high, along with RTCRST#, SRTCRST#, INTVRMEN# and PWRBTN#. That last one needs to be low for a short time after RSMRST# goes high, but you won't be able to check that without an oscilloscope.

If you still don't get PM_SLP_S4_L (nothing at all, no spike) maybe the RTC clock generator or some trace around there is bad. You need to check with an oscilloscope if it looks ok. Or anything that has an ADC, 32kHz is pretty low frequency so it should be easy to measure.
I don't see anything else but maybe I'm missing something. (could be the PCH but chances are low)

[Flippers McCoy]

Re: 820-00165-A Missing PP5V_S4RS3 and PP3V3_S4SW_SNS

Gotcha, gotcha, thanks

When I plug it in while reading PM_SLP_S4_L, it goes up to 1mV, then back down to .5mV where it stays, I don't think that counts as a spike?

How would I test the RTC generator if I have an o-scope? I got the datasheet for U1900, but I wasn't sure which pin to test for what at. I may be able to get my hands on an o-scope briefly at my university, but I wouldn't have a ton of time to hang out, I'd have to know what to look for before sitting down with it