[help] 820-01958 dead: 20v not switching

[phantomEVO]

hi to all! i have a macbook dead, already touched by some one...a lot of flux on the board excpecially on u7000.

i've found and removed a short on PP1SR3V3_G3H_P0V6_S3_VIN line.

Nowi have 5v@0,043 on both ports...no short around usb ic controller...any hint? thanks

i have a strange 2,6v on PP3V3_G3H_PMU_VDDMAIN and PP3V3_G3h

no shorts on those lines and good diode values...


help

[phantomEVO]

edit

[phantomEVO]

how is it possible to have 2,6 instead of 3,3??

[mon2]

Someone is causing this voltage rail to be lower. What is the exact resistance to ground of this rail? (No power during resistance checks).

What is the voltage to ground of PPBUS_G3H?

[phantomEVO]

PPBUS_G3H 12,25
PP3V3_G3h is like 180k
in diode mode 0,380

[phantomEVO]

PPBUS_G3H 12,25 i don't think it's normal

[mon2]

• PP3v3_G3H_RTC can also be pulled low by PP3v3_UPC_T_LDO or PP3v3_UPC_X_LDO, so if you have no measurable short to ground, and your enable/VIN is present, check both the above rails for a short or low resistance to ground. Low resistance to ground/short on the above LDO lines will usually be caused by a bad CD3217.

yes, ppbus_g3h voltage is low and can be linked to T2 communication fault.

[phantomEVO]

PP3v3_G3H_RTC is 3,3 rocksteady...no shorts or low resistence on PP3v3_UPC_T_LDO and PP3v3_UPC_X_LDO

[phantomEVO]

i try to recap what i've done since day 1 one.

found short on l7690

lift on leg, the short was on PP3v3_G3H

removed r5520, found the short on c8161 cap

the only mistake 've made: 3,3v injected on this rail (PP1SR3V3_G3H_P0V6_S3_VIN)..

[phantomEVO]

help

[phantomEVO]

i've triple checked PPBUS_G3H

the exact voltage is 12,28....

repair wiki said

~12.28–12.35 V = T2 communication issue with the ISL9240. The likely cause for this is the device is stuck in DFU mode due to corrupt T2

but i've tried to connect to my mac, and i can't go to dfu mode. as soon as i connect usb c (both ports),it says impossible to use this thunderbolt accessory

[mon2]

Locate the T2 SOC firmware chip and back it up. Then reflash this same chip and place it back onto the board.

Watch these videos on the topic:

https://www.youtube.com/watch?v=n164YwaI4cQ

https://www.youtube.com/watch?v=VtPuu-tDSto

Summary - there is a firmware IC that holds the code for the ACE controllers (CD321x series). If that firmware is corrupted, the macbook will be stuck @ 5v for the power delivery. By using external tools, you can reflash the SPI flash device and force feed a known good firmware image to fix what the DFU process is supposed to be doing. You still need to DFU after this transplant of the firmware IC but you are in a catch-22 cycle. Need the DFU to work to fix the firmware but the firmware is needed to be ok to allow for the DFU.

[phantomEVO]

so i have to read, backup and reflash the same firmware?

[mon2]

No. Back up the original firmware - CYA = 'cover your arse' (our company policy . Keep it in a safe place.

Then hunt for a dump of a known good T2 flash device - check the bios section of this forum for your model. It may be already posted. Use that firmware to reflash this target flash IC. We are suspecting at this time that the T2 firmware is corrupted.

Note that the T2 flash device is a funky shape and pinout. You will need a special adapter or PCB to host the IC and convert it to a PDIP for a standard flash programmer tool. Watch the linked videos to observe the shape and size. Aliexpress sells the adapters and sockets.

[mon2]

A2179 T2 rom dump:

https://www.badcaps.net/forum/troubl...rogrammer-tool
* see post # 7

This should do the trick.

T2 SOC ROM on A2179 = U4770

Be sure to back it up 2 times and verify the contents before erasing and reflashing with new firmware.

[phantomEVO]

i've already done a backup with my tl866II


i'm flashing it with the dump of post 7

[mon2]

You have an adapter for this odd shaped flash device? Nice.

[phantomEVO]

no...just some fantasy!

https://www.dropbox.com/scl/fo/str4b...=eh4mcp0x&dl=0

no luck...no dfu still the same...as soon as i connect usb c (both ports),it says impossible to use this thunderbolt accessory...then i go with this procedure without luck

https://www.youtube.com/watch?v=UaVgBP4gJsU

[mon2]

The flashing of this target IC went well with your setup? Erased and applied the posted T2 dump?

[phantomEVO]

Yes…I can try to reprogram it another time…But I don't think that anything will change