Macbook Air A2337 dead at 5V/0,00A

[Patrick501]

Hey,
I'm working on a MacBook Air M1. I'm pretty sure the U8100 is not working correctly. But I never had to change it before, so I wanna ask anyone of you guys to confirm (or not confirm) my thoughts on it.

USB Tester: 5V / 0,00A
PPBUS_AON: 12,3 V
PP5v_S2: 0 V no short
PP3v3_S2_UPC: 0 V no short
PP1v25_S2: 0 V no short
PPDCIN_AON_CHGR_R: 5 V
no enable signals for the S2 rails by the U8100


both CR3217 (UF400, UF500), are supplied by 5V (Fuses FF200 and FF201)
PP3v3_UPC0_LDO: 0 V, 0,5V diode mode to gnd
PP1v5_UPC0_LDO_CORE: 0 V, 0,5V diode mode to gnd
PP3v3_UPC1_LDO: 3,4 V; 0,5V diode mode to gnd
PP1v5_UPC1_LDO_CORE: 1,6 V; 0,5V diode mode to gnd
when I switch the power supply to the other USB-C Port, it's the other way around. So this looks fine to me as well.


schematics and boardview: https://www.badcaps.net/forum/troubl...creen-provisor
also I considered this https://repair.wiki/w/MacBook_Air_A2...w_at_5V_repair

[Patrick501]

I had some time to continue and I found out:
CC1 1,6V on UF400 and UF500 but CC2 is 0 V

Will it ever switch from 5 to 20V if CC2 is dead?

[mon2]

CCx are the communication lines for this 1 wire interface used by power delivery. There is CC1 on one side of the USB connector blade. CC2 will be on the opposite half of the USB connector. Only one CCx pin will be active so your measurements so far are accurate.

Remove the power plug and rotate it by 180 degrees to mate with the opposite half of the connector. Do you now see a voltage on CC2? CC1 will be at 0v since there is no connection on the original side.

If still @ 0v then suggest to flux and carefully remove the ESD device(s) on the CCx pin that is probably shunting this signal.

To debug, follow the general guideline for 20v and CD3215 controllers:

https://logi.wiki/index.php/CD3215_Bootup_Sequence

Start with confirming that each LDO rail on the CD321x controller is present. The BMC voltage of 1v1 will only be active for the active USB port. Only if each CD321x controller is not defective, then you will have 20v negotiated on the logic board.

Would you have a thermal camera? To check if there is a shorted part on the board that may be heating up.

[Patrick501]

thanks for your answer!

CCx are the communication lines for this 1 wire interface used by power delivery. There is CC1 on one side of the USB connector blade. CC2 will be on the opposite half of the USB connector. Only one CCx pin will be active so your measurements so far are accurate.

Remove the power plug and rotate it by 180 degrees to mate with the opposite half of the connector. Do you now see a voltage on CC2? CC1 will be at 0v since there is no connection on the original side.

If still @ 0v then suggest to flux and carefully remove the ESD device(s) on the CCx pin that is probably shunting this signal.

it switches, when I rotate the USB-C plug

To debug, follow the general guideline for 20v and CD3215 controllers:

https://logi.wiki/index.php/CD3215_Bootup_Sequence

Start with confirming that each LDO rail on the CD321x controller is present. The BMC voltage of 1v1 will only be active for the active USB port. Only if each CD321x controller is not defective, then you will have 20v negotiated on the logic board.

I found this link before on here. I think it's a bit different compared to my board since I have the CD3217 (screenshot attached)
I don't hvae the LDO's and HV_Gates which are listed threre. One or two positions are not even connected (for exampple SMC_RST)

PP3v3_UPC0_LDO: 0 V, 0,5V diode mode to gnd
PP1v5_UPC0_LDO_CORE: 0 V, 0,5V diode mode to gnd
PP3v3_UPC1_LDO: 3,4 V; 0,5V diode mode to gnd
PP1v5_UPC1_LDO_CORE: 1,6 V; 0,5V diode mode to gnd

I can easily find the bmc voltage on the CD3215 but not on the CD3217. Is there another name for it?

Would you have a thermal camera? To check if there is a shorted part on the board that may be heating up.

yes, I have one but there's nothing heating up.

[mon2]

https://logi.wiki/index.php/CD3217_a...er_on_Sequence


https://repair.wiki/w/MacBook_Pro_A2...w_at_5V_repair
* A2338 article but may be of help


Check each LDO rail on these CD3217 ACE controllers.

You can try a DFU.

[Patrick501]

https://logi.wiki/index.php/CD3217_a...er_on_Sequence


https://repair.wiki/w/MacBook_Pro_A2...w_at_5V_repair
* A2338 article but may be of help

according to this link and the one for the A2337 it could be a bad U8100.
PPBUS_AON is also a bit low by 12.28V /diode mode 0.527V

You can try a DFU.

I did a DFU twice, but this one won't connect. I also tried different USB ports. I think you can only use the two ports connected straight the logic board. Not sure though... neither of them worked

Check each LDO rail on these CD3217 ACE controllers.

there are the voltages of both CD3217. (USB-C connected to UF 400 first, then UF500)

[mon2]

PPBUS_AON is ok. It is not yet boosted after the SMBUS / I2C communication.

What is the voltage to ground of the following?

I2C_SMC_PWR_3V3_SDA
I2C_SMC_PWR_3V3_SCL

Test at battery connector J5150 (pins # 3 & # 4).

The LDO_3V3 rail @ 3v45 seems high. This should be 3v3 and may be of concern. Do you see this exact voltage on the 2nd CD3217 as well? This rail is used to power the SPI firmware boot flash used by these power delivery controllers. Share the above measurements.

[Patrick501]

What is the voltage to ground of the following?

I2C_SMC_PWR_3V3_SDA
I2C_SMC_PWR_3V3_SCL

I2C_SMC_PWR_3V3_SDA: 3.3V
I2C_SMC_PWR_3V3_SCL: 3.3V

Test at battery connector J5150 (pins # 3 & # 4).

3.3V both

The LDO_3V3 rail @ 3v45 seems high. This should be 3v3 and may be of concern. Do you see this exact voltage on the 2nd CD3217 as well? This rail is used to power the SPI firmware boot flash used by these power delivery controllers. Share the above measurements.

yes it's 3.43V on both now. I just double checked with another multimeter.

[mon2]

The repair wiki article (post #1) still notes that the voltage should be 3v3 for the LDO. The SPI flash is tolerant to 3v6 (max) so it should be ok.

See if this is your case here (ironically - still chasing a similar case on a high end iMAC):

https://www.youtube.com/watch?v=u4-66f6RFPM

[Patrick501]

See if this is your case here (ironically - still chasing a similar case on a high end iMAC):

https://www.youtube.com/watch?v=u4-66f6RFPM

I have the voltage (green) on the coil like in den video but no standby voltages in the red area.
Only the PP3V8_AON_VDDMAIN seems present

[mon2]

See if the attached helps.

[mon2]

The above should be complete for the power up voltage sequencing diagram. Wait...these are for A2338. Ok, need to drink my coffee. Will still leave it up there. Let me check if A2337 is available for the same.

Drugs...or not enough of:

A2337 (what I have)

[mon2]

Also see if this link works for you:

https://academy.chinafix.tech/shipin...SDgriR9LIHM_aA

[Patrick501]

mon2
thanks for the schematics. Unfortunately is has no numbers for the sequence like the one for the A2338 but I will try to figure this out.

For some reason I get private messages without text. Do you know what's wrong there?

[mon2]

I received your email - check if that came through ok on your side.

[Patrick501]

for anyone who has the same issue. I don't have a solution yet but meanwhile I checked the power sequences to get 20V.
Everything is fine until it reaches the U8100/U7700. There are no output signals, so apparently the sequence ends there. I also checked resistances of the missing output rails./ second step in diode mode.


35 ohm seems low but for a cpu rail it should be ok.

[mon2]

CPU rail resistance is ok.

Can you confirm your USB C meter with another load? Perhaps your phone? Does the meter report a non-zero current draw? The concern here is if the meter is unidirectional or bidirectional in design. Respectively, if unidirectional, the meter should be used in the direction of their marked arrows.

[Patrick501]

Can you confirm your USB C meter with another load? Perhaps your phone? Does the meter report a non-zero current draw? The concern here is if the meter is unidirectional or bidirectional in design. Respectively, if unidirectional, the meter should be used in the direction of their marked arrows.

I know what you mean, t's an unidirectional. I use it either with adapters or put it straight into the USB power supply to keep it in the right direction, 5.1V@V0,00A

[mon2]

From the repairwiki, missing S2 rails may be due to corrupt firmware.

CD3217 support S2 rails low or missing

https://repair.wiki/w/MacBook_Air_A2...w_at_5V_repair
* same as you cited in post # 1

I would consider the firmware replacement of U1970 before anything else.

[Patrick501]

I would consider the firmware replacement of U1970 before anything else.

I assume the only possibility to do this is the way it was done here?
https://www.youtube.com/watch?v=u4-66f6RFPM