Macbook Pro A1990 PP5V_G3S missing

[geiti94]

Hello to all

I have a macbook pro A1990 820-01814 that dont turn on

PP5V_G3S and PP2V5_NAND_SSD0 are at 0V instead of 5V and 2.5V

Someone have a sugestion where t start for find the problem?

i cant set the unit in dfu mode

[mon2]

What is the voltage and current draw of the usb c port being used to power the board?

Voltage to ground of ppbus_g3h?

For the above rails, measure their resistance to ground.

[Snazzysmith]

Check C9081. Just about every a1990 I have had had a shorted C9081. You can use schematics and boardview for 820-0141.

[geiti94]

What is the voltage and current draw of the usb c port being used to power the board?

Voltage to ground of ppbus_g3h?

For the above rails, measure their resistance to ground.

USB voltage i cant measure it since i still dont recived my usb meter.

ppbus_g3h have 12.3V measured at F7000 and F7001

PP2V5_NAND_SSD0 measured in continuity mode goes up to 975ohm and in ohm mode up to 28.9k

PP5V_G3S measured in continuity mode goes up to 1975ohm and in ohm mode up to 22.5k

i measured with the multimeter PP20V_USBC_TB_VBUS and PP20V_USBC_XB_VBUS and they are at 5V and when i try to measure ampere from there it stays at 0



@Snazzysmith

C9081 cap was completly missing and i put a new one on it.

that board got 4 months ago a waterdamage and got cleaner from a pc company and it worked 3 months. after 3 months he never turned on again

[geiti94]

ok got some strange behaviour from the device. sometime when i connect the charger to the top left port i get 20PP20V_USBC_XB_VBUS at 20V but then ppbus_g3h have only 3 to 5V

ok found out i get 20V only when i connect first charger to dfu port and then to an other usb port.

[mon2]

Is the original OEM charger from Apple being used for this laptop? Same power rating as recommended by the vendor?

Remove all power. Meter in resistance mode. What is the resistance to ground of ppbus_g3h? In post #4, the voltage is in the proper range so suspecting no issue here but the voltage is much lower in post #5. Suggest to flux and remove the fuse @ F7000 and F7001. Then power up again. Do you now have a stable and valid voltage on ppbus_g3h, everytime on this one working port?

What is the ppbus_g3h voltage if using other ports on the laptop (still with the downstream fuses removed)?

Review the CD3215 details here - each port on the board should be able to select the 20v power delivery contract:

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

[geiti94]

Voltage on post 5 goes down only when i connect first the charger to the usb c port used for dfu and then connect it to any other usb port. It habe then 20V on usb but only 3 to 5V on ppbus_g3h.

I am using an acer type c 65w charger. Tested apple one too and same happens. I am thinking problem comes from usb electronic since when i connect charger to dfu usb c port then i dont even get 5v from PP20V_USBC_XB_VBUS but i get then somehow 12V on ppbus_g3h

After i am at home i will check CD3215

[mon2]

The ISL regulator onboard is a buck boost type. If the input voltage is 5v then this ISL regulator will boost the voltage to 12v. However, if the input voltage is 20v to run the board in normal mode, then the same ISL regulator will enter buck mode where it will accept this higher voltage and lower it to a lower one of ~12v6 - ~13v (varies with macbook designs). A buck regulator mode will always supply higher currents than a boost regulator to operate heavier loads.

Do also inspect each USB type C connector for cat urine or similar issues with the contacts. This will impact the required CCx pins on the type C connector for communication with the power adapter. The power up default of all USB C power adapters is 5v. Only after a valid handshake of packets, will the logic board request the 20v power delivery (PD) contract.

[geiti94]

measured now everything with the apple charger.

all voltage up to PPDCIN_G3H are here. but the one that should have 20V have only 5V.

TBA_AUX_DET and SMC_RST_L i could not find it.

can be they stay at 5v because battery is not installed?

[geiti94]

checked now again the complete board for shorts and found nothing except the false positive of cpu rails since cpu have low ressistance.i am thinking to order some c3215 and try it if works then

[mon2]

Test that each LDO rail on each CD3215 is present. Something is incorrect with one or more of the CD3215 if the 20v power delivery contract is not being detected.

Report any suspects that may be missing a power rail. Note that the PP1V1_UPC_Tx_LDO_BMC rail will only be active for the port side that is active. USB C has 2 sides to the connector. Top side / bottom side (flipped connector by 180 degrees). The BMC rail is used for the 1 wire communication for the power delivery contract negotiations.

[geiti94]

measured now everything. 1 BMC is missing. and that is PP1V1_UPC_XA_LDO_BMC the one that use the usb c used for dfu. can i take the cd3215 from an icloud locked a1932 board?

[geiti94]

ok ordered now new c3215 + reballing stancil and 0.3mm solder balls. after everything is here i will replace the chip and report back

[mon2]

Be sure the CD3215 are with the same suffix as the original.

From this link - CD3215C00 should be suitable:

https://www.mobilesentrix.ca/usb-c-p...534-bga-96-pin

[geiti94]

yes i ordered CD3215C00 and not CD3215B or CD3215A. i ordered better flux now too so that i have then everything.

you think its better to use the solder balls for reballing the chip or soldering paste with melting point at 140c?

[geiti94]

so replaced the chip today but still same problem. what else it can be?

measured again ppbus_g3h and now it fluctuates from 3.3 to 9V but never to 12v

Update: Reballed and resoldered again the new chip. ppbus_g3h again 12V and PP1V1_UPC_XA_LDO_BMC is now here but mainboard still draws only 5.18V and 0.040A from what my usb tester say

[geiti94]

ok i am getting crazy with that board. smc_rst is for some reason only 1.8v instead of 3.3v. u7000 chip is defective?

[mon2]

Where are you measuring this voltage exactly? Use the full and exact netname from the schematic for debugging.

[geiti94]

since SMC_RST was not presend in A1990 Boardview i checked firsr A1706 one since they use same u7000 chip and saw it is on Pin 39. on A1990 the name is TP_CHRG_SMC_RST_L and there is a test point on the mainboard. there i get 1.8V instead of 3.3V. SMC_USBC_INT_L have an other name too on A1990. The Name is here UPC_I2C_INT_L and there i have 0V.

[mon2]

TP_CHRG_SMC_RST_L

does not exist on the A1990.

TP_CHGR_SMC_RST_L does on U7000 ball H4. It appears to be NC and is floating. Best to use cut & paste from the schematics.

Review U6940. This part is being powered by PP3V3_G3H_RTC_X so the output levels should be 3v3 (pin 10).

Can you confirm that you have a voltage on PP1V8_SLPS2R?