MacBook A2442 not powering on – suspecting CD3217, but replacement didn’t help

[TechSplendid]

Hi All,

I'm working on a MacBook Pro A2442 (14", 2021) that's not powering on. On two out of three USB-C ports, I get 5V and the current briefly ramps up to around 0.210A before dropping to 0.036A. On the third port (JF600), I only get 0.0045A and it stays there.

Initially, I suspected a faulty CD3217 on that port, especially since I noticed signs of previous liquid damage near the JF600 USB connector. I replaced the CD3217 with an UF400 (from an A2442 donor board from the same location). According to the supplier, this should be a compatible version, but the behavior didn't change at all.

I measured all the pins on JF600 in diode mode and compared them to values on OpenBoardData – everything seems to match.

I still suspect the CD3217, but since these chips are hard to source and verify, I'm wondering if anyone has seen similar symptoms or knows if this could be caused by something else?

Any input is appreciated!

[mon2]

Test the LDO rails of each and every CD3217.

[TechSplendid]

I'm not at home right now, but I'll measure that again later. What I did notice was: when I connect the charger to the JF600, I measure 0V on PPDCIN_AON. However, when I connect the same charger to a different port, I get 5V on PPDCIN_AON. That's why I still suspect the issue lies with the CD3217

[mon2]

Review the components linked to JF600. Be sure the USB C connector is not coated with cat urine or similar. Have seen some nasty connectors in our place that needed to be dunked inside of an IPA bath to be born again.

Review the resistance to ground of the PPVBUS_USBC0 line used by JF600. Perhaps the TVS @ DF622 or DZF620 has triggered from a past transient event.

[TechSplendid]

Thanks for thinking along, everyone. The connector (JF600) is fine, and all diode readings match the data in FlexBoardView. PPVBUS_USBC0 also measures correctly. DF622 and DZF620 also showed good diode readings.


I just measured PP3V3_UPC0_LDO, PP3V3_UPC1_LDO, PP3V3_UPC2_LDO, and PP3V3_UPC3_LDO again. What stands out is this: when I plug the charger into JF600, I only get 3.4V on the suspected CD3217, and 0V on the other CD3217s.
However, when I connect the charger to a different port, all CD3217s read 3.3V, with 3.4V on the CD3217 that belongs to that port.
So as far as I can tell, the issue really seems to be in the area around the CD3217 and JF600. I'm just not experienced enough to fully understand why I'm seeing this behavior.

Edit:
It just occurred to me that the ROM (UF260) might be the issue. Unfortunately, I don't have a donor board to test this. What do you think — could these symptoms be related to the ROM?

[mon2]

I believe the dump for that ROM is posted inside of the BIOS forum.

[TechSplendid]

Yep, found it already. Thanks! Gonna try it out tomorrow.

[TechSplendid]

Swapped the ROM chip, but no change unfortunately. Anyone have any ideas?

[TechSplendid]

I've done some more measurements. I hope I've presented them clearly this way. It's a bit of a maze for me since I'm not fully familiar with the workings of the CD3217 yet, but maybe someone with these details can shed some light on what might be going on. What stands out to me is that the CD3217 (UF400) doesn't provide USBC0_3V3LDO_EN and UPC01_5V_EN, regardless of which port I connect the charger to.

Charger on JF600 Measured on UF400
PPVBUS_USBC0 = 5.2v
PP3V3_S2 = 0.02v
PP1V2_S2 = 0v
PP3V3_UPC0_LDO = 3.456v
PP1V8_S2 = 0v
USBC0_3V3LDO_EN = 0v
UPC01_5V_EN = 0v
PPHV_INT0_AONSW = 0v
PP5V_S2SW_USBC01 = 0v

Charger on JF601 Measured on UF400
PPVBUS_USBC0 = 0v
PP3V3_S2 = 3.3v
PP1V2_S2 = 1.2v
PP3V3_UPC0_LDO = 3.3v
PP1V8_S2 = 1.8v
USBC0_3V3LDO_EN = 0v
UPC01_5V_EN = 0v
PPHV_INT0_AONSW = 5.1v
PP5V_S2SW_USBC01 = 0v

Charger on JF601 Measured on UF500
PPVBUS_USBC1 = 5.2v
PP3V3_S2 = 3.3v
PP1V2_S2 = 1.2v
PP3V3_UPC1_LDO = 3.4v
PP1V8_S2 = 1.8v
USBC1_3V3LDO_EN = 1.8v
UPC01_5V_EN = 0v
PPHV_INT1_AONSW = 5.1v
PP5V_S2SW_USBC01 = 0v

[mon2]

Be sure the batteries in your multimeter are fresh. The following rails appear to be too high to me.

[TechSplendid]

Yes, I noticed that too. However, the 3.4V is only present on the CD3217 that's connected to the port where I have the charger plugged in. On the other CD3217s, I do measure 3.3V. So I don't think that's the issue, unless all the CD chips are faulty. What I'm more wondering about is why I don't have USBC0_3V3LDO_EN on that one CD3217. Could this mean the replacement CD3217 isn't working properly after all, or could it be something else?