820-3437 not turning on

[Alan.L]

liquid damaged board. someone attempted repair this board, backlight driver is missing and has been ultrasoniced

green then orange light on magsafe 2 (genuine adapter), no fan spin, CPU does get little warm after a while.

- PPDCIN_G3H_ISOL = 16.66v
- PPBUS_g3H = 8,58V
- PP3V42_G3h = 3,41V
- PPV5_S5 = 5V
- PP3V3_S0 = 0.724V
- PP3v3 = 3,3V
- PP3V3_S3 = 0V
- PPVCC_S0_CPU = 0V
- PPVRTC_G3H = 3.294v
- PM_SLP_S3_L = 0.001V
- PM_SLP_S4_L = 0.001V
- PM_SLP_S5_L = 0.001V
- SMC_LID = 3.4v
- SMC_RESET_L = 3.4v
- PM_DSW_PWRGD = 3.429v

 

[Alan.L]

i cant tell if these chips has been replaced or just rework.

 

[dukefawks]

You can clearly see the solder blobs on some traces. Could be anything at this point, rabbit hole board that has been messed with, worst case.

 

[Alan.L]

the solder blobs on some traces are not shorted. should i leave this board?

 

[Alan.L]

PP5V_S0 is missing.
PP5V_S4RS3 is missing

U8080 create PP5V_S0


what create PP5V_S4RS3 ?


U7501 create P5VS4RS3_EN_R

P5VS4RS3_EN_R is 0v

pin14, pin29 of U7501 is 5v


bad U7501?

 

[dukefawks]

Why would U7501 generate its own enable. PM_SLP_S4_L is missing which is worst case. Check RTC voltages

 

[Alan.L]

U1900

pin1 = 3.294v
pin2 = 3.294v
pin12 = 0.391v
pin13= 3.432v


Y1905

pin1 = 1.005v
pin3 = 1.265v


i dont have a oliscope.



0v on PM_PCH_PWROK, SMC_DELAYED_PWRGD

 

[dukefawks]

Look at Louis's latest video on that 00165 board. This board is kinda the same caliber.

 

[larossmann]

Save yourself two hours, fast forward to 1:59:30 and do that part now. https://youtu.be/rvrCSntnhyM?t=7191

 

[Alan.L]

hahaha. maybe later, i haven't work on it yet. just diagnostic.