A2941 Macbook air 15” - 5V 0a

[obelix24]

ok that make sense.

Anyone any idea what can cause 5V 0.00A (sometimes it jumps to 0.01, 0.02, 0.03A) I tried thermal camera but this is not showing anything.

[mon2]

Insert this meter in series. Then test again. Show a pic of how you are testing. Be sure the meter is bidirectional use design. Some require the meter to be mated with the power adapter and then the usb cable powers the logic board. If truly at 0 amps, there is no load. Pretty sure the meter is not being used correctly.

[obelix24]

See attachments. In screenshots i left everything connected (trackpad, keyboard, battery) but even with everything disconnected (just bare board) it behaving same. Ampmeter is connected to genuine apple power adapter (96W)

[mon2]

Remain to test with the port with the 20mA which is still very low.

Remove all power. Meter in resistance mode. Measure the resistance to ground of every inductor that you see onboard. Report any suspected shorted rails.

This case will be difficult since there are no schematics available (yet).

[obelix24]

I will meassure. As i mentioned before schematics and boardview files can be used from 13” macbook air m2

[mon2]

Ok. Really curious on this case. Hope we can make some progress.

[khaahk]

If the PPBUS_AON is still 85ohms then it is too low. I had also 5V on USB-C and similar resistance on PPBUS_AON, in my case the problem was Q5800. After changing it 20V appeared. I don't have the machine anymore to make measurements though.

[obelix24]

in diode mode
PPBUS_AON - 0.435
PPBUS_3V3S2_VIN - 0.436
PPBUS_5VS2_VIN - 0.435
PP3V3_AON - 0.718
PP3V8_AON - 0.340
PP5V_S2 - 0.130
PPDCIN_USBC_AON - 0.157
PPHV_INT1_AONSW - 0.157
PPHV_INT0_AONSW - 0.157
PPHV_INT5_AONSW - 0.157

[mon2]

PP5V_S2 - 0.130

Diode mode is showing a lower than usual forward voltage drop. Now, switch to resistance mode on your meter.

Measure the resistance to ground on PP5V_S2. Post the resistance in ohms. Suspecting that the laptop was hit by some USB related transient which has led to the USB load switch or TVS ESD diodes being nuked.

[obelix24]

resistance on PP5V_S2 is 108 ohms.

[obelix24]

any idea ?

[obelix24]

Will injecting voltage show something ?

[khaahk]

Will injecting voltage show something ?

You'll have to inject and see, there is no way to tell it in advance.

Are some voltages present if you are saying that PPBUS is 12V, 3v8aon, 3v3aon?
If the board was working at first and stopped after waiting for the screen then water damage got worse. (was battery connected during this time?)
Visual inspection of the damaged areas not helping?

[obelix24]

Yes it was working and in the time waiting for new screen i let battery connected as i tested this macbook without screen with external display. Then put to shelf.

i noticed one thing when i try different amp meter i can see

one port is 5v 0a 9999.9ohm
but on the other port there is 5v 0.02-0.03a and ohms are sometimes 185ohms and sometimes it jumps to 9999.9ohm (on ampmeter) see attached photo

does this mean anything ?

[khaahk]

As the battery was connected some electrolysis process continued and now some connection is lost somewhere. Only visual inspection can help. Critical are parts which have positive voltage all the time and are important (ie boost circuit on smps). You did not answer about the PPBUS or AON voltages, are they present or not, which ones if any? Are there any differences if connected to the port which uses 0.02A?

Yes it was working and in the time waiting for new screen i let battery connected as i tested this macbook without screen with external display. Then put to shelf.

i noticed one thing when i try different amp meter i can see

one port is 5v 0a 9999.9ohm
but on the other port there is 5v 0.02-0.03a and ohms are sometimes 185ohms and sometimes it jumps to 9999.9ohm (on ampmeter) see attached photo

does this mean anything ?

If you are asking about the resistance shown on usb-c tester then it is probably just calculated from voltage and current information.