820-00165-02 missing PP3V3_S4SW_SNS rail

[cj_002]

Hey there,

Prologue:

I'm 4 days into component level repairs, still on my fist board an 820-00165-02 (coffee damage), no severe corrosion anywhere. I have (to the best of my knowledge) many of the "basic" rails present (see list below). However I'm failing at PP3V3_S4SW_SNS which is just showing 0,2 V (No short in diode-mode unplugged). According to schematics for 820-00165-A PP3V3_S4SW_SNS comes from U8050, however i´m missing the enable SMC_SENSOR_PWR_EN (no short in diode-mode unplugged).

Question(s):

1. As I'm following schematics for 820-00165-A what differences should i expect since i´m working on a 820-00165-02 board?

2. Finally the most obvious: Why no SMC_SENSOR_PWR_EN/PP3V3_S4SW_SNS.

Thankful for any help or tip.


I have the following rails:

PPBUS_G3H 8,6 V
PPBUS_S5_HS_COMPUTING_ISNS 8,6 V
PPBUS_S5_HS_OTHER_ISNS 8,6 V
PPDCIN_G3H_ISOL 15 V
PPDCIN_G3H 15 V
PP3V42_G3H 3,42 V
PPVRTC_G3H 3,33 V
PP5V_S5 5 V
PP5V_S4RS3 5 V
PP5V_S0 5 V
PP3V3_S5 3,3 V
PP3V3_S4 OK 3,3 V
PP3V3_SUS 3,3 V
PP3V3_S3 OK 3,3 V
PP3V3_S0 OK 3,3 V
PP3V3_S4SW_SNS 0,2 V
PP3V3_S0SW_SSD 3,3 V
PP3V3_S4_TBTAPWR 3,3 V
PP1V8_S3 1,8 V
PP1V2_S3 1,2 V
PP1V05_SUS 1,05 V
PP1V5_S0 1,5 V

[piernov]

Re: 820-00165-02 missing PP3V3_S4SW_SNS rail

You didn't go to the end of the power rails, especially PPVCC_S0_CPU, but this would look like the machine may turn on, even with a missing PP3V3_S4SW_SNS.

Still, strange behaviour. Any liquid near the SMC, U8050 or Q5500? What's the resistance to ground of SMC_SENSOR_PWR_EN?

Also check the voltages going into/out of U1950.

[cj_002]

Re: 820-00165-02 missing PP3V3_S4SW_SNS rail

Thank for your reply!
Cant see much corrosion anywhere.

Resistance: SMC_SENSOR_PWR_EN to ground = 600 ohms.

Voltage U1950:
pin1: 0,1 V
Pin2: 3,3 V
Pin3: 0 V
Pin5: 0 V
Pin6: 0 V
Pin7: 0 V
pin8: 3.42 V

[cj_002]

Re: 820-00165-02 missing PP3V3_S4SW_SNS rail

Also Vcore=0 V

[piernov]

Re: 820-00165-02 missing PP3V3_S4SW_SNS rail

With all the rails you have, ALL_SYS_PWRGD (pin 1 of U1950) should be high. If you feel like it you could check voltage on all pins of Q8150, and check voltage on R8164/R8165/R8166/R8167/R8168 but this is probably a dead end.

SMC_SENSOR_PWR_EN being only 600 ohms to ground is too low in my opinion, but I don't have any board to check on. You could remove Q5500 and U8050, and see if the resistance goes up.

But with weird measurements like that, it would point to an issue with the SMC. You may try to reflow it if you're confident.

[cj_002]

Re: 820-00165-02 missing PP3V3_S4SW_SNS rail

Unfortunately i don' t have this tools for that at the moment. However I just noticed that U7600 and U8080 gets really hot to the touch when i plug in charger, but i cant see how this could impact the 1.05 V rails as they come from the PP3v3_S4SW_SNS rail right?

[SMDFlea]

Re: 820-00165-02 missing PP3V3_S4SW_SNS rail

Why are U8080 and U7600 getting hot,and what do those IC`s have in common ? U8080 pin 2 P5VS0_EN .U7600 pin 16 P1V05S0_EN .
Look at the S0 Enables rail ,page 59 on the schematic.Test voltage,ohms on U8180,R8180,C8185,C8186,C8187.

[cj_002]

Re: 820-00165-02 missing PP3V3_S4SW_SNS rail

Why are U8080 and U7600 getting hot,and what do those IC`s have in common ? U8080 pin 2 P5VS0_EN .U7600 pin 16 P1V05S0_EN .
Look at the S0 Enables rail ,page 59 on the schematic.Test voltage,ohms on U8180,R8180,C8185,C8186,C8187.

Hi,

Thanks for your input! On U8180 i have:
Pin 1&2: 3 V
Pin 5: 3.3 V
Pin 4: 5 V (is this to high?)

I also checked the resistors and caps you asked for: C8186= 4.98 V however I'm missing R8180, C8185 and C8187, it seems as if they were never placed on the board ill attach image:

[SMDFlea]

Re: 820-00165-02 missing PP3V3_S4SW_SNS rail

My bad,those parts are "no stuff" ,i must have been tired.... . What else does U8080 and U7600 have in common, U8080 pin 1 PP5V_S4RS3 ,U7600 pin 12 PP5V_S4RS3 . Check PP5V_S4RS3 voltage,check if its stable .

[cj_002]

Re: 820-00165-02 missing PP3V3_S4SW_SNS rail

My bad,those parts are "no stuff" ,i must have been tired.... . What else does U8080 and U7600 have in common, U8080 pin 1 PP5V_S4RS3 ,U7600 pin 12 PP5V_S4RS3 . Check PP5V_S4RS3 voltage,check if its stable .

U8080 and U7600 both have enables from U8180. Since U8180´s output is 5V on both P5V_S0_EN (U8080) and P1VP5S0_EN (U7600) this might be why they get hot? U8180 being a logic gate should just output the 3,3 V from PP3V3_S5 right? However the board seems to be in S0 state since all S0 rails are present and stable except PPVCC_S0_CPU. Not sure how to proceed.