Macbook pro 820-2936 not charging ppbus 12.27v - strange it posts

[justin35]

Mbp 820 2936 board
Laptop came in with no green light.
Pp3v42 was shorted to ground. It turned out to be isl 6259.
I injected 2v@1amp on pp3v42 line and u7000 got worm.
I replaced u7000 and the board post has chime but not charging battery.
U7000 pin 17/18 3ohms pin 27/28 20ohms
Ppbus_g3h is 12.27v !!!
Green light appears after 3-4seconds it flickers a few times then it's solid green and fan starts to spin.
I tried to run ads test but it get stuck on loading asd ... board freezes mouse light goes off
I did reflow smc, no luck
Changed again u7000, no luck
I reballed smc, no luck
Smc data lines for u7000 are ok...
If i plug in battery+magsafe, when i disconnect magsafe, it runs from battery...
I never encountered this problem, ppbus 12.27 instead of 12.5+v and board posts

Thanks!

[piernov]

Re: Macbook pro 820-2936 not charging ppbus 12.27v - strange it posts

Could be bad SMC.
Is battery percentage correct in macOS?
Did you check PPBUS_G3H with battery and BIL disconnected?
SMBUS diode mode measurements are the same within 1% for both SDA and SCL?

[shibu]

Re: Macbook pro 820-2936 not charging ppbus 12.27v - strange it posts

hi can you check without connect battery the pp3v42 is there

[justin35]

Re: Macbook pro 820-2936 not charging ppbus 12.27v - strange it posts

I could not load os, because is very slow... so i don’t know if the battery percentage is there.
It even doesn’t load ads from usb...
Ppbus measure without battery and bil connector installed and unistalled ... (same voltage)
Sda scl in diode mode red probe on ground 0.57 and 0.47 so there is like 20% percent difference?!?
One resistor measure 1998ohm and one 1820 ohm... swapped the lower resistor with a 1950ohm but it’s also pulled down to 1800ohms because of the circuit...
I think is the smc?!

Thanks!!

[piernov]

Re: Macbook pro 820-2936 not charging ppbus 12.27v - strange it posts

Yeah if you measured diode mode with everything disconnected, it's probably the SMC itself. (since charger IC has been replaced already)

[justin35]

Re: Macbook pro 820-2936 not charging ppbus 12.27v - strange it posts

Charger ic was replaced twice... from donors boards... i refuse to believe it had the same fault ...
I'll try to find an other smc

[qonma]

Re: Macbook pro 820-2936 not charging ppbus 12.27v - strange it posts

This problem solved???? I have same problem....only can on with battery