macbook a1708 no power

[madjid911]

HI, I have a macbook A1708 820-00840-A, won't turn on, no shorts, no liquid damage, well tripped 20v but no current draw.

Measures :
PPBUS_G3H 13V
PPDCIN_G3H 19V76
PP5V_S5 3 to 5V unstable
PP3V3_S5 0 to 3V3 unstable
3V3_S5 0 to 3v3 unstable
PP3V3_G3H 3V4

SN650839 have some voltages coming out:
PP5V_LDo5V 5V
PP3v3_LDO3V 3V3
PPBUS_PMIC 13V
PP1V25_VREF 1V3

Do you have an idea please ?

[mon2]

Re: macbook a1708 no power

Remove all power. Meter in resistance mode.

Measure the resistance to ground of:

PP5V_S5
PP3V3_S5

Power up. Measure the voltage to ground of:

P3V3S5_EN
P5VXX_EN

[madjid911]

Re: macbook a1708 no power

Remove all power. Meter in resistance mode.

Measure the resistance to ground of:

PP5V_S5
PP3V3_S5

Power up. Measure the voltage to ground of:

P3V3S5_EN
P5VXX_EN

I replaced the u7650 but the result is the same
PP5V_S5 290 K
PP3V3_S5 24 K
3V3S5_EN 47 K
P5VXX_EN 47 K

The measurements seem good to me but I can't find where the problem comes from.

[mon2]

Re: macbook a1708 no power

Power up. Measure the voltage to ground of:

P3V3S5_EN
P5VXX_EN

[madjid911]

Re: macbook a1708 no power

Power up. Measure the voltage to ground of:

P3V3S5_EN
P5VXX_EN

P3V3S5_EN 0V Δ 3V4 instable
the same for P5VXX_EN 0V Δ 3V4 instable

[dellxps15]

Re: macbook a1708 no power

must be some short on s4 s3 s0 rail. check resistance on that rails.

[madjid911]

Re: macbook a1708 no power

must be some short on s4 s3 s0 rail. check resistance on that rails.

I found the problem, c2977 in bad condition, by dint of doing tests and disconnecting and reconnecting, c2977 is shorted, I was then able to identify the short circuit and replace c2977, now all the voltages are stable and the macbook comes alive. Thanks for your help

[dellxps15]

Re: macbook a1708 no power

glad u fixed it man good work