a1990 820-01814 liquid damage - missing s5 rails

[shlomim412]

Hello

having issues with a1990 820-01814 logicboard
was stuck on 5v
liquid damaged on U9080 area

replaced u9080 and cleaned underneath, also replaced c9080 which was corroded.

after that was drawing 20v with low amperage (0.06-0.08)

after removing the heatsink i found alot of corossion on U7370 area and U9850

i replaced U9850 and reflow U7370 and surrounding caps \ resistors..

now still getting 20v 0.08-0.05.

i found out missing pp3v3_s5 and pp1v8_s5

assembled the mac, trackpad is clicking but no image, the machine DOES goes into dfu but fail to restore\revive with error -
AMRestoreErrorDomain – 0x6 (6)


any ideas?
i have a good board to compare measuring to but not sure where to begin...

any help will be appreciated.
thanks..

[mon2]

Re: a1990 820-01814 liquid damage - missing s5 rails

Hi. It is fauda

Yours may be the last case here:

https://repair.wiki/w/A1990_2018-201...ar_MacBook_Pro

[shlomim412]

Re: a1990 820-01814 liquid damage - missing s5 rails

Hello mon

thanks for the quick answer

will try to replace u3000, will have to order this one :|



but in general - the error - AMRestoreErrorDomain – 0x6 (6)

means problem with the ssd?
how can i determine if the ssd is ok or not on this board?

[mon2]

Re: a1990 820-01814 liquid damage - missing s5 rails

Hi. The link was shared for a review to check if the fault is the same as yours. Do not replace the component till we have a confirmation the part is defective.

Check with a thermal camera or even IPA over this part. If the alcohol evaporates quickly then the component is heating up.

Check your SSD voltages.

https://boards.rossmanngroup.com/thr...a-0-93a.62713/

[shlomim412]

Re: a1990 820-01814 liquid damage - missing s5 rails

hi

checked with IPA over u3000, doesn't seem to get warm or evaporates the IPA faster than surrounding chip \ caps...

ssd voltages seem to be ok
getting
2.5v on PP2V5_NAND_SSD0
1.79v on P1V8_LX0_SSD0
0.89v on PP0V9_SSD0

i don't have thermal camera, but from what i can tell
the ssd chips are getting a little bit warm, and ofcourse cpu and gpu is cold (no vcore)..

[mon2]

Re: a1990 820-01814 liquid damage - missing s5 rails

Voltage to ground of ppbus_g3h ?

[shlomim412]

Re: a1990 820-01814 liquid damage - missing s5 rails

it's 12.6 and than dropping to 12.28 than back to 12.6 and again 12.28\9

it's cycling like this on ppbus_g3h...

[mon2]

Re: a1990 820-01814 liquid damage - missing s5 rails

Remove fuses F7000 and F7001.

Then measure the voltage to ground of PPVBAT_G3H_CHGR_REG at F7000, pin #1 (ISL = producer side of this rail).

What is the measurement without the downstream consumer load?

[shlomim412]

Re: a1990 820-01814 liquid damage - missing s5 rails

with f7000 and f7001 removed i measured 12.27-12.28v on pin #1 of f7000..

[mon2]

Re: a1990 820-01814 liquid damage - missing s5 rails

Remove all power. Measure the resistance to ground of F7000, pin #2 (consumer side).

What is the measurement?

[shlomim412]

Re: a1990 820-01814 liquid damage - missing s5 rails

it's showing 0.0 at the beginning and than 1.2 K ohm and climbing up to 4K + and keeps climbing...

measured with red probe to ground.. (this the correct way to go?)
either way all power removed...

[piernov]

Re: a1990 820-01814 liquid damage - missing s5 rails

PPBUS_G3H is fine.
Damage on 2.5V SSD regulator very often means dead SSD ICs. Measure resistance to ground on both rails SSD0/SSD1.

[shlomim412]

Re: a1990 820-01814 liquid damage - missing s5 rails

only have ssd0 on this specific board...

PP2V5_NAND_SSD0 is 30 ohm to ground :|
much lower than good working board..

rest seem to be ok...

is it worth to inject voltage? or simply dead ssd?

[piernov]

Re: a1990 820-01814 liquid damage - missing s5 rails

You'll probably see SSD ICs slowly warming up on thermal camera. They need to be replaced, after making 100% sure all power circuitry is good (so that it doesn't kill replacement SSD ICs).

[shlomim412]

Re: a1990 820-01814 liquid damage - missing s5 rails

in cases of a short like this, all ssd chip are damaged?

how do you advise to make sure all is good, before installing new ssd ic's?
the short should be gone after the bad ssd ic's are removed?

[piernov]

Re: a1990 820-01814 liquid damage - missing s5 rails

All of them may be damaged, but you could always inject voltage and remove ICs getting hot under thermal camera one by one.
After removing the bad SSD ICs, resistance to ground should come back to a few kiloohms on the 2.5V rail.
Make sure there's no corrosion left around and under the buck controller, and make sure all the voltages are good and stable before putting replacement SSD ICs in.

[shlomim412]

Re: a1990 820-01814 liquid damage - missing s5 rails

thank you very much for the help

if ssd ic's comes from donor board of same model
what should i look for? solder each one back to the same place?
in case like this they need to be programed?