820-01700 A2141 ppbus 12,3v

[2informaticos]

This is how Apple builds new machines.
You can try 100 times DFU and doesn't complete.
Then, after some days, weeks (maybe never), you may have luck and complete DFU.

 

[Bravo2001]

Ohh really?!? That really is shitty... So just keep on trying to restore!?


Another question, does DFU mode require a working Keyboard and screen. Because I received this repair only with topcase, without screen. And don't now for sure if keyboard is working.

 

[2informaticos]

You can use SWK003 pads, without connecting keyboard.
Must connect charger with pads closed, then open pads after 3-10s; or when you see it on AC2.

 

[Bravo2001]

I tried not many many times but every time it fails. Do you have any other options?

 

[2informaticos]

I bet for T2 internal problem...

 

[Bravo2001]

Wauwww, After months I the closet. I have an update... I flashed the T2 rom file just a hell Mary and connected on a battery with a charge in it and it is recognized as in DFU. After DFU restore I got an Apple logo.

Because it won't charge I can't complete the setup, to check for further problems (if any)

So looks like it will work on battery but now it won't charge.

PPBUS_G3H with battery is 11.3V
PPBUS_G3H without battery is 12,3V

Amp meter on all ports 20v 0.100a with no batt connected
Amp meter on all ports 20v 0.030a with batt connected.

I have a working 820-01700 But don't now where to start comparing...

Feel like im olmost there

 

[2informaticos]

Is that battery working with the good board?
Be sure to use 96/140W charger.

 

[Bravo2001]

Yes the battery works with a good board. And I use a 100W Not original but good Branded charger. Which also works with other good Board... Should this make a difference?!

Did some measurements. Think it has something to do withPPBUS_G3H which is 12.3v on this board and should be 12.6V.

 

[2informaticos]

There is no good communication between U7000 and T2 (SMC).
That's the reason of incorrect PPBUS_G3H and not charging battery.

Compare diode mode and voltage readings around U7000 and Q7065/70 between both boards.
Try changing U7000.

 

[Bravo2001]

Checked all diode mode readings for u7000 all are similar to working board.

Also changed u7000 stil same issue...

What else can disrupt communication between u7000 and t2? Could it have something to do with u4770 SoC Rom? But it works with Batt so SoC rom shouldn't be the issue...

 

[Bravo2001]

Also as you can read, this board had some issues before... Around UB090 USB-Rom chip. Could that have effected the communication with T2.

 

[2informaticos]

Does the machine work with charger alone (no battery connected)?
All USB-C ports have the same behavior?

A problem with TBT ROM shouldn't allow charger to switch from 5V to 20V; on the corresponding ports (without battery).

 

[Bravo2001]

No, without battery doesn't work. Machine works on battery with charger connected but doesn't charge.

I tried a SoC Rom flash. Didn't do a thing...

All USB-C port have same behavior...

 

[2informaticos]

TBT ROM is involved, so may have a problem there.
Check traces and adjacent components for U2890/B090.

 

[Bravo2001]

Before I look at the TBT rom area. I noticed that after I flashed the SoC rom with the working one. It now stays in DFU mode. Even when I restore or revive it can’t complete and always stays in dfu mode…

Also put back the original Rom file, can’t get it to boot with battery to anymore.

 

[2informaticos]

Maybe the heat applied several times on the board affected T2, or CPU.

 

[Bravo2001]

Ok, got it back to working on Battery...

Need some help figuring out why ppbus won't go up to 12.6v

Feels like im so close!

 

[2informaticos]

You can't get 12.6V with only battery.
What is PPBUS_G3H voltage now (charger alone)?
What you've done to make it works again with battery?

The charger used (not original) works with good board without battery connected?

 

[Bravo2001]

PPBUS_G3H is 12.25v charger alone. I did another dfu restore and it works with battery and charger connected. Amp meter shows 20v 0.1a. I bought original 96w Apple charger.

Charger works with good board perfectly.

Today I saw a Spanish video (used CC with translation) on YouTube

Who had same issue, and he changed all USB-C Controllers… and got PPBUS back to 12.6v.

I checked all pins of CD3217 with diode mode (easy job with S-UEM2 recommend to everyone!

)

Maybe reflashing TBT rom?

 

[2informaticos]

You can try reflashing TBT ROMs; make backup first.
Some peoples complain on Internet that CD3217 chips give problems on A2141 machine.
You may need to change them from donor board, same model.