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820-3437 not turning on

Alan.L

Alan.L

Member
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
 
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Alan.L

Alan.L

Member
looked like work has been done. area between spi rom and smc.


spi rom
2wfmo83.jpg



right side after spi rom

U1900 =
29dik3k.jpg



Y1905 =
wiaqyr.jpg




below spi rom

U7400 =
t9du84.jpg



U7501 =
28a2iv8.jpg




above SMC
j9yezk.jpg




...shit, i realised these.
 
Last edited:
D

dukefawks

Administrator
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.
 
D

dukefawks

Administrator
No they are not shorted. It does mean someone fucked with it and gave up. At this point there is no telling what happened to the board. Only continue with this if you have nothing better to do.
 
Alan.L

Alan.L

Member
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?
 
Last edited:
Alan.L

Alan.L

Member
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
 
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