[SOLVED]820-3208 missing ALL_SYS_PWRGD and others.

[MUUK]

820-3208


Had powered USB device inserted, now does not turn on. No liquid damage, no burnt components that i can see
green light present, goes to orange.
CPU stays cold, PCH U1800 gets warm.


PPBUS_G3H = 8.34v
PPBUS_S5_HS_COMPUTING_ISNS = 8.38v
PPBUS_S5_HS_OTHER_ISNS 8.36v
PPVRTC_G3H = 3.3v
PP5V_S5 = 5.13v
PP3V3_S5 = 3.3v
PP3V3_S4 = 3.3v
S5_PWRGD = 3.4v
PM_SLP_S4_L = 3.3v
P5VS3_EN = 3.3v
PP5V_S3 = 5.1v
PP3V3_S3 = 3.3v
PP5V_S0 = 5.12v
PP3V3_S0 3.3v
PP1V8_S0 1.797v
PP1V5_S0 = 1.5v
PM_SLP_S3_L=3.3v

ALL_SYS_PWRGD=0.04v

Q7950 ALL_SYS_PWRGD=0.04v
pin1 0.741v
pin3 0.093v
pin4 0.04v
pin5 0.7v
pin6 0.131v
pin7 0.77v

CPUVCCIOS0_PGOOD= 0.05v

U7600
CPUVCCIOS0_PGOOD= 0.05v
pin13/14 = 5.1v
pin3 = 3.2v
pin10=1.05v


PP0V75_S0_DDRVTT= 0v
MEMVTT_EN = 0v
PM_SLP_S3_L=3.3v
R2810 - pin1 3.3v pin 2 0v (measures fine at 10k)

Q2810

pin 5 PLT_RESET_L = 0v
pin 2 & 3 = 5v


So i am missing:

CPUVCCIOS0_PGOOD
PLT_RESET_L
ALL_SYS_PWRGD
MEMVTT_EN
PM_S0_PGOOD


Wen to go look back at USB looked at U2600

VCC 3.3v

U4600
pins 3 & 2 = 5v
pin4 = 3.3v
pin5 = 0v
pin7= 0v
pin8 (unconnected but)=0.5v
pin9= 0v
pin10= 3.3v

The fact the PCH is getting warm makes me think it is dead / shorted, but i can't see any burnt or damaged components.
I've failed in trying to work out which one of the missing rails should come first. I suspect that PLT_RESET_L is the big problem.
Would appreciate any suggestions before moving on ?

 

[smiba]

The system is trying to get into S0 and already partially is in a S0 state, there is no surprise the PCH is getting warmish.

You are probably missing a power line, check why ALL_SYS_PWRGD is not there:
Voltage of PP3V3_S5_VMON, PP3V3_S0_VMON, VMON_3V3_DIV, PP1V5_S3RS0_VMON, PP1V05_S0_VMON?
R7953-R7956 within resistor specification?

 

[dukefawks]

There is a rail missing and it is not PP0V75_S0_DDRVTT cause that one is not in the PGOOD sequence. Voltages on Q7950 are ok so ALL_SYS is pulled down by R7963-66 and friends in that area. Measure voltages on both sides of them.

 

[MUUK]

Thank you for your replies.


R7963
pin1 PVCCSA_pgOOD = 0.17V
PIN2 ALL_SYS_PWRGD = 0.05V
MEASURES 99OHM

R7964
PINS 1& 2 0.05V
CPUVCCIOS0_PGOOD=0.05V
MEASURES 99OHM

R7965
PIN1 p3V3s5_pGOOD=0.05V
PIN2 ALL_SYS_PWRGD=0.05V
MEASURES 100OHM

R7966
PINS 1& 2 0.05V (P1V8SO_PGOOD)
MEASURES 99OHM

R7967
PIN1 PP3V3_S0=3.3V
PIN2= 0.05V
MEASURES 2.1KOHM (UNDER BUT NOT A PROBLEM)

R7901
PIN1 & 2 0.05V
P3V3S5_PGOOD = 0.05V
MEASURES 77OHM


PP3V3_S5_VMON MEASURED AT PIN 1 R7956 3.3V, PIN 2 0.131V
MEASURES 149KOHM


PP3V3_S0_VMON MEASURED AT PIN 1 R7951 3.3V PIN 2 0.766V
MEASURES 8,8K (SUM OF DIVDER I BELIVE)

PP1V5_S3RS0_VMON MEASURED AT PIN1 R7955 1.34V PIN 2 0.774V
MEASURES 990OHM

PP1V05_S0_VMON MEASURED AT PIN 1 R7955 1.1V PIN 2 0.79
MEASURES 1KOHM

SO I AM MISSING

PVCCSA_pgOOD
CPUVCCIOS0_PGOOD
P3V3S5_PGOOD


TRYING TO FIND P3V3S5_PGOOD FIRST WE DO HAVE P3V3_S5 AT 3.4V

LOOKING U7201
PIN20 P3V3S5_PGOOD 0.05V
PIN21 P3V3S5_EN_R 3.4V
PIN12 P3V3S5_REG_EN 3.4V
THIS HAS ENABLES, AND PP3V3_S5 IS PRESENT SO GOING TO LOOK AT THE OTHERS


PVCCSA_pgOOD
U7100
PIN14 0V.
PIN19 = 5.12V
PIN20 (PP5V_S0) = 5.12V
PIN15 (en)=3.2V
PIN14=0.017V
PIN12=0V

C7140 (PIN11) DOSEN'T LOOK RIGHT SO REPLACING.
DIDN'T CHANGE ANYTHING
R7141 & 7142 BOTH MEASURE 1KOHM
U7100 HAS POWER, AND ENABLE PUT IS NOT TURNING ON.
IT LOOKS FINE.


P1V8S0_PGOOD
(P1V8_S0 is present)
U7200
PINS1,2,3 = 3.3V
PIN5(EN) = 3.3V
PIN7 = 0.05V

Once again, has power, has enable but is not putting out PGOOD.

is it worth pulling r7963, r7964, r7965 to see if one rail is pulling them all down?
Thanks for any help.

 

[dukefawks]

TLDR.

There must be a voltage drop on R7963-66. The ALL_SYS side will be lower than the PGOOD signal side. This will be the one pulling the rest down. Voltage drop will only be a 50mV or so, so measure carefully. No need to pull them all.

 

[MUUK]

Sorry for the long previous post.
You were correct as usual duke. PVCCSA_pgOOD was the problem and pulling the others down.
U7100 looked fine, had enables and voltage but was not turning on.

Replaced U7100 (and USB chip). Machine now working fine. Thank you may mark as closed.