Macbook no life a1278 board 820-2327

[stevieh2o]

have an old macbook showing no signs of live
magsafe lights up green then turns to orange
iv got the schematics and did some testing but cant see whats at fault, can anyone help me?

i tested along the pp3v42_g3h
u6990 and got
1 -15.5v
2 unconnected
3 15.5v
4 ground
5- 3.4v
6-6.7v
7-3.4v
8-1.23v

c6995 3.39v
r6995 3.39v
c6999 3.39v

c4650 and got 3.4v
r4650 and got 3.4v
u5403 pin 3 3.39v pin 4 12.45v pin 5 12.45v

c7046 pin 1 2v pin 2 got 12.45v
r7047 pin 1 12.45v pin 2 12.45v
r7031 pin 1 12.45v pin 2 12.45v
c7041 pin 1 5v pin 2 ground
c7040 pin 1 5v and pin 2 ground
r7010 pin 1 16.5v pin 2 3.9v and 29.6kohms

can someone point me in the right direction...

[piernov]

Re: Macbook no life a1278 board 820-2327

List power rails instead of random parts on the board.
Also you say you have green light so it's useless to check the parts that are responsible for it.
And you haven't described the symptoms (fan doesn't start spin after pressing power button? no chime? no image? etc…) or the history of the board.

[disorder]

Re: Macbook no life a1278 board 820-2327

hi

take the schematics, look at power rails list and test all of them one by one untill you find one not corresponding tell us.
then you'll have to check which component could cause the line not working : first check if you have short with diode mode.

[MobileXT]

Re: Macbook no life a1278 board 820-2327

what is voltage on PPBUS_G3H without the battery?

[stevieh2o]

Re: Macbook no life a1278 board 820-2327

what is voltage on PPBUS_G3H without the battery?

checked the ppbus_g3h 2.7v at r7801

[stevieh2o]

Re: Macbook no life a1278 board 820-2327

List power rails instead of random parts on the board.
Also you say you have green light so it's useless to check the parts that are responsible for it.
And you haven't described the symptoms (fan doesn't start spin after pressing power button? no chime? no image? etc…) or the history of the board.

No fanspin no signs of live at all
No water damage etc

Wouldnt switch on a few months ago so i opened it up and got it going using the powerpads. worked for a few months now dead again.

[stevieh2o]

Re: Macbook no life a1278 board 820-2327

3.3v at PP3V3_S5

No power getting to PP5VRT_S0 at r 9302

[MobileXT]

Re: Macbook no life a1278 board 820-2327

checked the ppbus_g3h 2.7v at r7801

your PPBus_G3H is low suppose to be 12.54v check that power rail. I'm guessing you have a PP3V42_g3H present.

[piernov]

Re: Macbook no life a1278 board 820-2327

It is not possible to have 3.3V on PP3V3_S5 when PPBUS_G3H is 2.7V. Please double check your readings.
Also note that R7801 has nothing to do with PPBUS_G3H.