820-3115 no chgr_acok

[Bouba148]

Hi Team

I have a 820-3115 which had a lot of issues: No DCIN : fixed was Q7085 shorted to ground
Then PPBUS_G3H shorted to ground, fixed was Q7030 and Q7035 shorted to ground
Now the ISL doesn't turn it's pin 1 to ground to switch Q7085
PP3V42: OK 3,47V
PPBUS_G3H: 1,4V but slowly going to ground
Pin 2 PPCHGR_DCIN: fluctuating between 16,4V and 16,7V
Pin 3: OK 4V
Pin 14 CHGR_ACOK : 0V
Resistance 17/18 OK: 3,3 Ohms 27/28 20,2 Ohms

Now I'm suspecting the ISL.
Is there anything else to check before i replace the ISL

thanks

Finally I've replaced it and PPBUS_G3H is 12,56V

Now I've a quarter fan spin.....let me go throught it and check which rail is missing

 

[Bouba148]

Here are my mesurements:

PPBUS_G3H : 12,51
PP3V42_G3H :3,471
PPVRTC_G3H :3,326

5V Rails:

PP5V_S5 (PP5V_S5_LDO) : 4,997
PP5V_SUS : 4,994
PP5V_S3 : 0V
P5V_3V3_SUS_EN : 3,326v
SMC_BATLOW_L : 3,297V
PM_SLP_SUS_L : 3,325v
SMC_RESET_L : 3,437V

3.3V Rails:

PP3V3_S5 :3,326V
PP3V3_S4 :0,6v BUT PULSE TO 3,3v
PP3V3_SUS : 3,324v
PP3V3_S3 : 0v BUT PULSE TO 3,3v

U7200 VOLTAGES:

P5VS3_ENTRIP: 0V
P5V3V3_REG_EN: 3,453V
P3V3S5_ENTRIP: 0,769V


U1800 Level :
PM_SLP_S4_L : PULSING TO 3,3v
SYSCLK_CLK32K_RTC : 32KHZ OK
PP3V3_ENET_SYSCLK : PULSING
SMC_ADAPTER_EN: 3,436 OK
PM_PCH_SYS_PWROK : 0V

ALL_SYS_PWRGD: Pulsing
PP5V_S0: Pulsing
R7402: OK

PM_SLP_S3_L: Pulsing

I've replaced C3898 it was bad looking and bad value (2,5uF vs 4,7uF) , also replaced R5481 and R5482.
Now I'm suspecting U1800: corroded or bad

Could you please give your feeling

THANKS

 

[SMMRepair]

Still a short somewhere, maybe 3v3 or 5v rail, board is cycling...if you found all that other stuff damaged/killed, this one might have several issues. Was this liquid or bad charger?

 

[dukefawks]

Was this liquid?

 

[Bouba148]

It look like that in fact it was liquid damaged

 

[Bouba148]

R5123 was missing : THAT FIXED THE QUARTER FAN SPIN, it's directly involved in the SPI Bus
C1713 was also missing
also i didn't reported it, but i had 2 brokens traces around U7000 one in the R17/18 loop and in the 27/28 loop.
Now had to put back every thing together to check if all the functions are fine.

 

[Bouba148]

So here are the last news:

When i've reassembled qll together, i had no chime, no display, fan increasing speed until it stoped, board overheating.
The overheqting was because U3890 was shorted to ground, i revomed it and continued my troubleshooting without it as it's used for the thunderbolt.
at that point nothing overheating on the board but still same behavior regarding the fan ( increasing speed until it stops).
all my main power rails looked OK, then i checked the voltages PPVCORE_S0_CPU and PPVCORE_S0_AXG both were 0V with low resistance to ground.
I decided to remove R7510,R7520,R7550 and R7640 looking for a short to ground, nothing found but after replacing back all those 4 resistances the fan doesn't spin anymore but just a tiny pulse when the charger is plugged.
so i went throught all the rails again and this is what i have:

PPBUS_G3H : 12,56
PP3V42_G3H :3,471
PPVRTC_G3H :3,326

5V Rails:

PP5V_S5 (PP5V_S5_LDO) : 5,105
PP5V_SUS : 5,102
PP5V_S3 : 5,107V
P5V_3V3_SUS_EN : 3,326v
SMC_BATLOW_L : 3,296V
PM_SLP_SUS_L : 3,325v
SMC_RESET_L : 3,437V

3.3V Rails:

PP3V3_S5 :3,326V
PP3V3_S4 :3,325v
PP3V3_SUS : 3,323v
PP3V3_S3 : 3,326v
PP3V3_S0 :3,320v

PP1V8_S0 : 1,798v
PP1V5_S3_DDR : 1,506 v


U7200 VOLTAGES:

P5VS3_ENTRIP: 1,120V
P5V3V3_REG_EN:3,453V
P3V3S5_ENTRIP: 0,769V


PM_SLP_S4_L :3,317v
SYSCLK_CLK32K_RTC : 32KHZ OK / 0,417V
PP3V3_ENET_SYSCLK : 3,314v
SMC_ADAPTER_EN: 3,436 OK
PM_PCH_SYS_PWROK : pulse to 0,49 then 0V

ALL_SYS_PWRGD: 0,020V
PP5V_S0: 5,104V
R7402: OK

PM_SLP_S3_L: 3,306V

PP1V5_S3_CPU_VCCDQ : 1,505v
PP1V05_S0 : 0,014v with 54 ohms to ground when power and 4,5 Ohms to ground without power
PPVCORE_S0_CPU : 0,001V with 5,9 ohms to ground with power and 2,1omhs without.
PPVCORE_S0_AXG : 0,000v wtith 1,5 ohms to gound with power and 1,3 ohms without.

With R7640 Removed:

Nothing on pin1 of L7630 mesured also with the scope.

U7600 VOLTAGES:
CPUVCCIOS0_EN: 3,264V
PP5V_S0_CPUVCCIOS0: 5,103v
UGATE AND NGATE no signal on the scope except one pulse on UGATE
U7600 replaced and still the same

 

[jadao]

You are in S0 state but missing PP1V05_S0.
You will not have all_sys_pwrgd without It.

Not sure but it looks like you are measuring resistance with power applied.

I don't have a board in front of me to compare but I think 4,5 ohms on the missing rail is low. If no short look around U7780 see if voltage rails on pin 3, 4 and 6 are present.

 

[Bouba148]

Hi Jadao,
thanks for your answer: apparently I have all the correct voltages around U7780, on pin 1 I have 1,057V, but if i mesure this rail around U5511 for example I mesure 0,020V.
But what you asking me to mesure is PP1V05_S0_LDO which is different from PP1V05_S0 see page 7. Am I wrong?
Also I'm mesuring 362Ohms between those "2" rails.
I've noticed that i've forgot to put back R7640 sorry.
Now it's done and the fan is spining but increases until it stops

 

[jadao]

Oh sorry, scrap this, nothing to do with pp1v05_S0_ldo!
Your problem is PP1V05_S0. Make sure by comparing with another 3115 there is no short on this rail. I can check resistance for you tomorrow.
Q7630 is suspect. There is low value resistors in U7600 circuit, check them to make sur all ok.

 

[Bouba148]

HI Team,

here are the last voltages mesured for this board, after ultrasonic cleaner, fan progressively spin to max speed, board not getting hot, no chime, smc re heated with flux, no ALL_SYS_PWRGD, CPU and DDRVTT voltages:

ALL_SYS_PWRGD : 0v
PP1V8_S0 : 1,802V
PP1V5_S3_DDR : 1,506
PP1V5_S0 : 1,516v
PP0V75_S0_DDRVTT : 0v RESISTANCE TO GND 1,4KOHM
PPVCCSA_S0_CPU : 0,904v
PP1V05_SUS : 1,040v
PP1V05_S0 : 1,056V
PP1V05_S0_PCH_VCCADPLL : 1,059V
PPVCORE_S0_CPU : 0V
PPVCORE_S0_AXG : 0V
PP1V5_S3_CPU_VCCDQ : 1,506V
PP1V05_S0_CPU_VCCPQE : 1,056v
PP1V8_S0_CPU_VCCPLL_R : 1,796V

Can someone explain me how Q7510, Q7520, Q7550 and Q7560 are working please, i couldn't find the datasheet on google.
Should i suspect the SMC?

Thanks

 

[dukefawks]

ALL_SYS is not present so there must be a rail missing. PPVCORE is not involved in this, once ALL_SYS comes high then you need to worry about PPVCORE. Check voltages at Q7950