820-00165 Green light, in S0 state, no fan spin

[Neil250]

removed:

R8166
R8165
R8164
R8168
Q8150

ALL_SYS_PWRGD PULSING : 0 -->3.33V--->0 --->3.33V

 

[2informaticos]

The S3 and S0 voltage pulse too now?
PM_SLP_S3_BUF_L is not steady anymore?

 

[Neil250]

S0 PULSING
S3 PULSING
PM_SLP_S3_BUF_L PULSING

0--->3.33V-0--->3.33V

Fan intermittently will do a quarter spin
BUT

AT U8180
PIN 4:
i will get a steady 3.33 randomly with FULL FAN SPIN!!!
IF
PM_SLP_S3_BUF_L STEADY at 3.33V= fan spin

 

[2informaticos]

What happens to loose steady voltages?
Now ALL_SYS_PWRGD pulses as normal, if the power rails pulse.
Check the work you did on the board...

 

[Neil250]

OK you were correct
Removed U1950 cleaned pads
Carefully replaced
Now with fan spin

Stable

ALL_SYS_PWRDGD AT 3.33
PM_SLP_S3_BUF_L STEADY at 3.33V

I still don't have voltage on CPU coils...but i got fan spin and stable voltages as above

Plan:

PUT BACK:

R8166
R8165
R8164
R8168
Q8150

 

[2informaticos]

Put back resistors one by one and check ALL_SYS_PWRGD each time.
Let Q8150 at the end, or throw it directly.

 

[Neil250]

is the fact that cpu voltages are not present expected?

 

[2informaticos]

VCORE appears after ALL_SYS_PWRGD.
So is time to get it.
Be sure to get voltage on all other big coils first, including page 57.

 

[Neil250]

replace

R8165 ---->FAN SPIN GONE ALL_SYS_PWRGD GONE
R8166 --> FAN SPIN GONE & ALL_SYS-PWRGD GONE


please note that with all resistors off

PIN 1 R8165= 0.1V --->P5VS4RS3_PGOOD
U7501 is also 0.1V

U7820
PIN 2: 3.33V
3:0.1V (not short to ground)
6: 0.8 V ----> should be 1.8V (not short to ground)
8:1.8V

 

[2informaticos]

"6: 0.8 V ----> should be 1.8V"
Do not make wrong assumptions; pin 6 is connected to a resistor divider (feedback signal)!
There is also noted a formula where you can get the exact voltage of pin 6; yes, is 0.8V.

R8167 also serves as pull-up resistor for all power good signals connected to ALL_SYS_PWRGD.
When you disconnect one resistor, what do you expect to get at its "left" side???

I saw several times failing 1V8 power good signal.
The board should work without R8165, if you get 1V8 power rail correctly; even if its power good is not OK.

 

[Neil250]

i lose fan spin when i replace

R8165
R8166

Should i be losing fan spin as i replace the pwrgd resistors?

As the resistors went in ALL_SYS_PWRGD went away.

ALL_SYS_PWRGD seems to get pulled down when i replace either of the resistors which is strange because wouldnt that mean 2 power rails have issues.

P1V8S3
P5VS4RS3

That may be a faulty asumption. I was assuming that the ALL_SYS_PWRGD signal must stay present as each rail is re-connected.

Again i think i may be not understanding the logic there.

MacBook logic board power rails and ALL_SYS_PWRGD - IT-Tech Online

MacBook power management discussion. S3 power rails, S0 power rail and ALL_SYS_PWRGD voltage

www.it-tech.com.au

 

[2informaticos]

The resistors are good, no need to replace them.

Don't you get fan spin removing only R8166?
This is what I understood before...

 

[Neil250]

Maybe I explained wrong

SEQUENCE
Remove R8166 ----> NO FAN SPIN
Remove R8165 ----> NO FAN SPIN
Remove R8164 ----> NO FAN SPIN
Remove R8168 ----> NO FAN SPIN

At this point all of the above resistors are off this board

Remove Q8150 -------> FAN SPIN


The only thing that makes the damn fan spin is removing Q8150 and... ALL_SYS_PWRGD is back

Put back Q8150 ----> NO FAN SPIN
Remove Q8150 -----> FAN SPIN

So lets put back R8166 with Q8150 off the board? -----> FAN stops spinning

 

[2informaticos]

I said you can throw Q8150.
You have a problem with resistor dividers on its inputs.
But this chip is not really needed, just a redundant protection.
Resolder the other resistors, without Q8150.

 

[Neil250]

informaticos:

So lets put back R8166 with Q8150 off the board? -----> FAN stops spinning

I tried putting back:

R8164
R8165
R8166
R8168

The fan, as I said above, goes away.
ALL_SYS_PWRGD....goes to 0

 

[2informaticos]

You MUST put back resistors one by one.
See when the fan stops spinning...