A2941 Macbook air 15” - 5V 0a

[obelix24]

I’m working on one macbook air 15” m2 that was water damaged.

keyboard, lcd, microphone connectors were damaged so i’ve replaced all of them and without screen connected macbook worked fine. Keyboard &trackpad and also lid sensor was working fine.

i’ve put macbook in shelf and order new screen so i can fully repair it.

Now i got the screen and macbook stays at 5v 0a.

i’ve tried if it’s not in DFU with another macbook but it’s not detected at all.

i don’t have schematics so i don’t know where to start can someone help me?

[mon2]

At true 0A current consumption, hunt for any onboard fuses that may be damaged from a transient event.

[obelix24]

yes but i don't have boardview so it's hard to find fuses

[obelix24]

I don’t know where fuses on this board are i’ve checked the white ‘fuses’ near CD32XXXXX are and they’re all good. Have someone boardview file for this macbook ?

[mon2]

Post a pic of your USB C meter while measuring the current draw. The current draw is 0.00A? Or do you have a few mA of current draw?

Again, if stuck at 0.00A then you do not have a proper connection to the logic board. Much like floating the power adapter in the air.

[obelix24]

It's 0.00a i saw maybe one or two times 0.01-0.02a for approx second but i can't replicate this. I tried more times leave adapter connected, connect / reconnected. ... but still 0.00a

[mon2]

Remove all power. Meter in resistance mode. Measure the resistance to ground of the fuses. Measure the resistance to ground of each inductor. At 0.00A, you have a disconnect of the power adapter to the board or a dead short on the board.

[obelix24]

it looks like boardview can be used from this board : 820-03285

I've checked fuses around CD3217 chip in diode mode and they all looks good. (0.576 both sides)

I've checked PPBUS_AON on some caps and in diode mode i get only 0.085 this looks to me too low. If i try in resistance mode i get 85ohm on this caps. should it be so low ?

i've it's the same then i have 9ohm on PP3V8_AON and also on some others like PP3V8_ATC01_VDDIO_REG

[obelix24]

i'm really confused.

I tried to replace all 3 UR700, UR760 and UR730. UR760 have damaged pad on the IC.

But macbook is still behaving same only 5V 0.00a

i've checked all fuses around CD3217xxxxx chips and they're ok.

Also i've checked all big caps on board and they're ok.

I've tried multiple times with another macbook if it's not in DFU / recovery, but it's not.

One time but i don't know how and why when i've connected screen the screen turns on and goes over some weird test (white, green, blue, it looks like when in factory they're testing screens if there are no burned pixels or so. in that time also caps lock was responding (there was green light) and also trackpad was clicking ...

Any idea what should i do / check ? i've found on logi wiki that CD3217B13 are not interchangeable with CD3217B12 (i've only this one's on spare boards) but i don't know if it's still true that you can't replace CD3217B13 with other IC's and you can use only the same CD3217B13 from the exact same location on board.

[obelix24]

any idea anyone ?

[obelix24]

I’ve checked all caps arround CD3217 and they’re all good. Also i’ve checked more caps on board and i’m not able to find any short.
tested usb-c port with usb-c mechanics tester and both ports looks ok.

any idea how to proceed or what can cause the problem 5v 0a ?

maybe faulty cd3217b13 ic ? Have someone tried to replace this chip with cd3217b12 is it still blocked ?

[obelix24]

I’m checking more and more.
there is still only 5v 0a on usb-c ampmeter

PPBUS_AON 12.29v

[obelix24]

i noticed one very strange issue.
When i connect USB-C port's (there are 2 ports) and there is power to one port the other port's getting output (it turn's ampmeter even if it's only bare ampmeter connected no cable connected to ampmeter)
I've compared if this is normal on another macbook (a2442) and if there is connected power and bare ampmeter it's not turning it on.

I've checked the port's and they looks ok.

[mon2]

Which exact USB-C port is showing these symptoms?

[obelix24]

both ports. It's really strange as ports on these macbook are separate parts (it' not like on old macbooks where 2 ports were together)

[obelix24]

mon2 do you have any idea what can cause this ? maybe it's the reason for 5v 0a

[obelix24]

Ok i male mistake only one port is doing this strange thing
i've checked and one port was little water damaged. Cleaned it and it is doing the same. I tried another usb-c port from a2442 and it's doing exactly the same

[mon2]

You are not using the meter correctly.

Insert the power adapter cable into the rear of the USB-C meter and test again.

[obelix24]

I know that this is not how it should be used 🤣 i'm just wondering if this is normal behavior. Because i gues the ampmeter should not light up when there is no power going dorectly into it. Does it not mean that there is short somewhere ? Or this is not the problem ?

[mon2]

This is not a problem. Just like the older usb connector, vbus from the logic board can be used to power usb devices like usb keyboards or USB mice, etc. If a power adapter is mated with the port, then the direction of vbus will reverse after the CCx pin communication and then the power adapter will send the voltage into the logic board for that port only.