820-01521 - Missing PP1V1_UPC_XB_LDO_BMC - 5V 0.236amp

[ronaldo]

I tough it may be useful for everyone with the same problem.
PP1V1_UPC_XB_LDO_BMC Missing.
This line is created by TB ROM (U2890) this IC has its own firmware.

All LDOs on the CD32 ON, except PP1V1_UPC_XB_LDO_BMC

I've replaced both USB-C controllers 2 times,
ISL9240HI (U7000),
W25Q80DVUXIE (U2890),
R2802 resistor,
TPS51980A (U7650).
All replaced and same results.

Resistor R2802 had 3.29V on one side 1 - PP3V3_UPC_XB_LDO and 0.62V on side 2 - TBT_X_SPI_MISO. The resistor is ok.
So, the other side of the resistor was missing TBT_X_SPI_MISO (3.29V) and this line is created by TBT Titan Ridge - Thunderbolt™ 3 Controllers (U2800).

After replacing this big IC it started to get 20V and 2.2Amp, but cycling.
It was probably because I don't have the correct stencil to re-ball it and solder it properly. When removing it I heard a pop sound.

I need the Stencil for this IC that I bought from China.

I will come back later to post my findings.

 

[2informaticos]

"This line is created by TB ROM (U2890) this IC has its own firmware."
Error, this LDO comes from U3200.
In fact, only connects with C3204; for stability purpose.
Is only used internally by U3200, for BMC communication with charger.

BTW, 1V1 LDO_BMC must appear only on the CD3215 chip corresponding to the powered port.
Corrupted TBT ROM (U2890) can impide CD3215 chips to boot correctly.
Then none of them generates 1V1_LDO.

TBT_X_SPI_MISO voltage comes from PP3V3_UPC_XB_LDO, trough R2892 (pull-up resistor).
Is a SPI data line and can't be diagnosed only be a DC voltage.
If no activity on that SPI bus, it should stay high to 3V.
Damaged chip connected to it, can drop the voltage; U2800 in your case.

Machine should boot without U2800, but may have problems with USB communication.
TBT function will be lost, of course.

You've followed a good repair way, but try to avoid wrong assumptions...

 

[ronaldo]

Thanks for your correction of my assumption.
I'm still a beginner and learning a lot with you.
It will improve my skills in future repairs and help more people with this issue.