Macbook pro A1278 no power with led green on magsafe

[opethfan]

Hi!
this is my first macbook and i'm trying to repair it.
I have read many posts but they can't solve my problem.

on the mainboard there isn't any burnt component and the main fuse is ok.

in the picture you can see my first measures near the main connector.
Hope someone helps me

[dellxps15]

Re: Macbook pro A1278 no power with led green on magsafe

post picture of the other side.

and post voltage on the 2 spot ive marked.

[opethfan]

Re: Macbook pro A1278 no power with led green on magsafe

thanks for your reply

[opethfan]

Re: Macbook pro A1278 no power with led green on magsafe

here others measurement

[opethfan]

Re: Macbook pro A1278 no power with led green on magsafe

here others

[dellxps15]

Re: Macbook pro A1278 no power with led green on magsafe

making measure all around the board without a logic is no sense. this big thing with all 0 volt is lan filter..... useless to measure for now.

i asked for 2 measure on these 2 coils (inductor) in my previous post.

next report voltage on green zone.

total 2 measure+ 1 ground.

u should have on green spot (white fuse) 12.5 volt ;
3.42 on the other green marked area.

if u have 3.3 volt on coil, u have 12.5 volt on that green marked fuse, and if u have 3.35 or higher (not over 3.42) u can put a fan, some ram slot, lvds connector with lcd and short that circled 2 dot on mainboard with a wtezer (smc bypass) and see if macbook start normally.

before all that, make sure u understand that procedure right. shorting those 2 pins should make your macbook start, so put fan, ram ecc ecc and be carefull to not short anything else. put all component on a non conductive zone.

u can try with magsafe only,with battery only , and with both.

any throuble, ask before act.

[opethfan]

Re: Macbook pro A1278 no power with led green on magsafe

in the green marked zone i have 12.5, the same voltage on the near white fuse

[dellxps15]

Re: Macbook pro A1278 no power with led green on magsafe

there are 2 green marked zone.. one left (white fuse) one circled green with short write. post voltage on those 2 pads. one is ground so no voltage, but the other should have voltage around 3.42volt.

[opethfan]

Re: Macbook pro A1278 no power with led green on magsafe

ok

[dellxps15]

Re: Macbook pro A1278 no power with led green on magsafe

follow procedure of smc bypass by shorting green circled mark (3.45volt and gnd) with ram and fan connected and report if macbook start.

[opethfan]

Re: Macbook pro A1278 no power with led green on magsafe

it doesn't start...

[dellxps15]

Re: Macbook pro A1278 no power with led green on magsafe

report voltage in marked green coil (inductor)

suspect u misisng 3.3 volt as bios doesnt have 3.3 volt.

[opethfan]

Re: Macbook pro A1278 no power with led green on magsafe

there are 3.3 volts on that coil

[dellxps15]

Re: Macbook pro A1278 no power with led green on magsafe

down the arrow there is bios chip. post voltage.

(the other one in first picture was lan chip)

[opethfan]

Re: Macbook pro A1278 no power with led green on magsafe

0 volts on every pin of bios chip

[dellxps15]

Re: Macbook pro A1278 no power with led green on magsafe

voltage on these 2 component and those 2 resistors ?

all marked with circle green

[opethfan]

Re: Macbook pro A1278 no power with led green on magsafe

ok

[dellxps15]

Re: Macbook pro A1278 no power with led green on magsafe

someone already put hands on this board i think

missing component marked with green circle.

code: u7740

component: TPS720105

[opethfan]

Re: Macbook pro A1278 no power with led green on magsafe

as you can see in this picture, that chip in not present on the same motherboard...

[dellxps15]

Re: Macbook pro A1278 no power with led green on magsafe

on my schematic it was not mentioned "no staff" .... weird apple


report voltage on that chip.
also in the near resistor.

also normal and while shorting the 2 spot i mentioned before (3.45 and gnd)