MBA 820-01521-A dropping PP5V_G3S (macbook restarts during boot)

[Mrsina77]

Hi,

I have liquid damaged macbook air 2018. Macbooks restarts after 10s when its trying to boot.
Q7660 was water damaged and I have cleaned everything. It is connected to the U7650 that makes the PP5V_G3S. When its trying to turn on than everything voltage seems fine and than it drops and after 10s its trying to boot again and again.

Anyone to help me to solve it?

Thanks for reply.

[mon2]

Re: MBA 820-01521-A dropping PP5V_G3S (macbook restarts during boot)

Review this thread which may be your case - update this thread for future readers:

https://boards.rossmanngroup.com/thr...07/#post-72889

[Mrsina77]

Re: MBA 820-01521-A dropping PP5V_G3S (macbook restarts during boot)

Review this thread which may be your case - update this thread for future readers:

https://boards.rossmanngroup.com/thr...07/#post-72889

Thanks for reply but this is not close to my problem.

When I have cleaned the board than my macbook turned on for 5 times (I was testing it). Next day macbook only restarts. So it means the macbook was somehow working but something happened. When I plug in the trackpad MB keeps restarting faster.

[mon2]

Re: MBA 820-01521-A dropping PP5V_G3S (macbook restarts during boot)

When it boots, do you have a display with the backlight and can see the usual apple logo?

Leave the track pad off if it is causing a faster power cycling.

[Mrsina77]

Re: MBA 820-01521-A dropping PP5V_G3S (macbook restarts during boot)

When it boots, do you have a display with the backlight and can see the usual apple logo?

Leave the track pad off if it is causing a faster power cycling.

Yes I do have backlight. Earlier I have seen Apple logo but now without apple logo. I was trying to do reset SMC or NVRAM. First try after this reset I am able to see apple logo. After 10sec macbook restarts and no apple logo, only backlight. All I have found was that PP5V_G3S is droping voltage for a while that cause the restart of MB.
Trackpad is off.

[mon2]

Re: MBA 820-01521-A dropping PP5V_G3S (macbook restarts during boot)

Remove all power. Meter in resistance mode.

Check the resistance to ground of PP5V_G3S.

Post the resistance and scale used on your meter for this measurement.

[Mrsina77]

Re: MBA 820-01521-A dropping PP5V_G3S (macbook restarts during boot)

Remove all power. Meter in resistance mode.

Check the resistance to ground of PP5V_G3S.

Post the resistance and scale used on your meter for this measurement.

Resistance on the line is very low (under the 1ohm).
Resitance to the ground falls down from XMohm to XX Kohm.

[mon2]

Re: MBA 820-01521-A dropping PP5V_G3S (macbook restarts during boot)

Remove all power. Meter in resistance mode.

Then one meter probe on this rail. Other meter probe to ground. This test will show us the resistance to ground.

What is the resistance again? Also interested in the meter scale for this same measurement.

Perhaps you can take a pic of your meter as well ?