Noob question

[PPVCC_S0_CPU]

Hi, i am diagnosing macbook air, it have no pp3v42 and ppbus_g3h.
my question is that can ppbus_g3h present without pp3v42?
initially ppbus_g3h was present but then when i replaced lt3470a and powered board on, smoke came out of l7030 and ppbus_g3h stopped working, since then i have removed lt3470a and replaced isl6259 but still ppbus_g3h is stuck at .80 volts

 

[2informaticos]

Never change any piece without measure the board.

Check now for short on PPBUS_G3H and 3V42 lines.
If no short at all, post ISL6259 voltages.

Maybe you can tell us which board you have on the desk...

 

[PPVCC_S0_CPU]

Its 820-2796.
I will post voltages in few hours.
There's no short on ppbus_g3h but i have noticed that pin 23/24 of isl6259 have very low resistance and multi-meter beeps on diode mode. I have replaced chip and q7030 but nothing changed

 

[2informaticos]

"pin 23/24 of isl6259 have very low resistance and multi-meter beeps on diode mode"
Do you mean with ground, or between 23-24?

Be aware beep is not equal short.
Multimeters beep until 060-075 indication on buzer/diode mode, depending of model...

PPBUS_G3H and 3V42 are independent rails.

 

[PPVCC_S0_CPU]

It beeps between 23 and 24 and its beeps continuously and value does not climb

 

[2informaticos]

That means ISL6259 detects a problem with PPBUS_G3H and short G-S of Q7030, to protect the system.
That "short" will normally disappear in time.
If Q7030 is shorted (beeps) D-S too, then is burnt...,