820-01521 20v 0A

[JdYoda]

Hi, got this mac a1932 for repair. Board looks clean, never been repaired before, no corrosion or traces of liquid damage

Bare board with no battery stays at 5v 0.09-0.1 amps
When battery connected - switching to 20 volts, 0 amps

Didn't find any short on board.
F6700 was blown, changed with new one
L7030 had a small crack, also changed
U7000, Q7030, Q7040 changed


PPBUS_G3H 12.2
PP3V3_G3H 3.3
PP3V3_G3H_RTC 3.3
PP3V3_G3S - 0
P3V3G3S_EN - 0

Enable signal for PP3V3_G3S comes from U7800, replaced it with a new chip, no changes
There should be some power lines created before PP3V3_G3S to make U7800 start work and send out enable signal?

Mac can be recognized in DFU state, reviving or restoring device ends up with an error.

Any ideas guys?

 

[2informaticos]

What error do you get on DFU?
Remove small audio board and check for liquid sign on its both sides.

 

[JdYoda]

AMRestoreErrorDomain, Error 6 - Failed to handle message type StatusMsg (Operation failed)

And i noticed that board is always in DFU mode. As soon as i plug in cable from one mac to another - it shoes up DFU mode

 

[2informaticos]

Looks like T2 problem.
Board shouldn't go to DFU on its own; unless SOC_FORCE_DFU signal is hardware forced.

 

[JdYoda]

Is it possible to install T2 from donor board and restore firmware? Or reball it? Never tryed to fix T2...

 

[2informaticos]

You can experiment few things, if have time.
First step, replace T2 and check what happens in DFU.
If no good, replace SOC ROM too.
Also NANDs chip may need to be replaced.
Be aware, all these MUST be from the same board.

 

[JdYoda]

Oh, i thought i can use any T2 chip...Don't have the same donor board at the moment. Ok, anyway thank for helping!

 

[2informaticos]

If changing only T2 chip is not sufficient, means it requires some specific data stored in ITS SOC ROM and ITS NAND chips.
You can try with any T2, but if need to replace all these chips, there could also be some data corresponding to a particular board model.