Macbook pro 820-2879 no 5V rail

[andiukas223]

Hello, I'm trying to fix a macbook 820-2879 that is not turning on, green light on the charger is present.
ppbus_g3h is 12.57V
pp3v42_g3h is 3.42V
No liquid damage
i tried to power on the machine by shorting the pins- no fan spin.

On L7220 3.3V is present, on on L7260 5V not present so i checked Q7221 pin 2 and p5vs3_en_l is 3.27V, pin 5 is low. Next i checked Q7891 for PM_SLP_S4_L and it is not present. I tough't it might be bad q7891 so i replaced it, but still no 5v enable signal.

I am certain that because of lack of knowledge and skill i am missing something.

I ask you to help a young noob

[piernov]

Re: Macbook pro 820-2879 no 5V rail

You need to trigger power button (short power button pads) while measuring PM_SLP_S4_L.
Also, confirm all G3H/S5 rails are ok, confirm you are using a known good 60W/85W Magsafe, and confirm you are troubleshooting without anything connected to the board, except DC-in and fan.

[andiukas223]

Re: Macbook pro 820-2879 no 5V rail

Thank you for replying Piernov, i seem to have shortened something in attempt to test PM_SLP_S4_L and it got my quite sad at this point. I will get back to this in the near future .