MacBook Air A1932 820-01521 no boot 5v only

[obelix24]

Hello,

I've one MacBook Air a1932 board number 820-01521
it's stuck on 5v (0.03 - 0.4a) - I've replaced 2x CD3215 for know good ones. It's still on 5V only and when I connect it to another MacBook it's just connecting and disconnecting.

I've checked PPBUS_G3H and the voltage it's not stable (it's still going up and down)

is there any voltage regulator ? or what should I check ?

I've also checked diode mode PPBUS_G3H on test point near CD3215 and I get 0,474

[mon2]

Re: MacBook Air A1932 820-01521 no boot 5v only

Each cd3215 must be working to dial up the 20v power delivery contract from the power adapter.

Check the voltage to ground of each LDO rail on each cd3215.

Remove the fuse on PPBUS_G3H. Power up again and measure the voltage to ground of the producer side (ISL) of the removed fuse.

Post each measurement. Start with the fuse removal.

Is PPBUS_G3H voltage now stable without the fuse?

[obelix24]

Re: MacBook Air A1932 820-01521 no boot 5v only

I've removed F6700

on one side of the fuse point it's still jumping ...

voltage on PPBUS_G3H is still not stable still jumping 6v,7v,11v,12v

XA_LDO and XB_LDO both have 0v

[mon2]

Re: MacBook Air A1932 820-01521 no boot 5v only

Measure the voltage to ground of PP3v3_UPC_XA_LDO and PP3v3_UPC_XB_LDO.

Remove all power and configure meter into resistance mode.

Measure the resistance to ground of each, PP3v3_UPC_XA_LDO and PP3v3_UPC_XB_LDO.

Post each measurement.

[obelix24]

Re: MacBook Air A1932 820-01521 no boot 5v only

ok I've tested both and they look ok (XB I've tested on test point, XA I've tested on C3108)
PP3v3_UPC_XA_LDO - 9Mohm (and going down)
PP3v3_UPC_XB_LDO - 9Mohm (and going down)

[mon2]

Re: MacBook Air A1932 820-01521 no boot 5v only

Resistance is fine but you really need to post the requested values. Otherwise, no one can help.

[obelix24]

Re: MacBook Air A1932 820-01521 no boot 5v only

what values ? voltage I got 0v there

[obelix24]

Re: MacBook Air A1932 820-01521 no boot 5v only

I have another MacBook Air same board that is probably more fixable.

I get on it 20V but 0a (when everything is disconnected) if I connect battery the A go up to approx 1,5A.

Strange is that PPBUS_G3H is present 12,64V but when I check it on L7030 I'm getting only 10V there (but it should be 12,64V)

[mon2]

Re: MacBook Air A1932 820-01521 no boot 5v only

Hi. Not an issue. As long as PPBUS_G3H is stable, the inductor @ L7030 is doing its job. The switching regulator is pulsing on/off to dial up the target voltage. So the PPBUS_G3H is working as it should.

The spike of a stable current draw is of concern and often means some component is shorted or is partially shorted.

[obelix24]

Re: MacBook Air A1932 820-01521 no boot 5v only

where should I search for a short ? Inject voltage somewhere ?
I've checked board under microscope but I'm not able to find any blown component or anything obvious.

[mon2]

Re: MacBook Air A1932 820-01521 no boot 5v only

Something does not look right if you are reading 0A current draw yet you have PPBUS_G3H voltage rail.

How is the current draw being measured? Is it a USB Type-C meter? Be sure that the meter is bidirectional in design. We know that we picked up at least 1 meter from Aliexpress that is unidirectional so it reports 0A current draw due to the way it is connected to the power source and the load.

Post a pic of the USB-C meter. Also review if there are arrows on the opposide side of this tool. If the meter is used in reverse, the meter will not properly report the current draw.

[obelix24]

Re: MacBook Air A1932 820-01521 no boot 5v only

I'm measuring on USB-C meter (KEWEISI)
see photos both ports from both sides

[obelix24]

Re: MacBook Air A1932 820-01521 no boot 5v only

ok I've checked :
PPBUS_G3H - 12,64V
PP3v3_G3H_RTC - 3,3V
PP3v3_G3H - 3,3V
PP1v8_SLP_S2R - 1,8V
PP1v8_AWAKE - 1,8V
PP1v8_SLPS2R_PMUGPIO - 1,8V
PP1v1_SLPS2R - 1,1V
PP0v8_SLPS2R - 0,8V
PP0v82_SLPDDR - 0,82V
PP3v3_AWAKE - 3,3V
PPVDDCPUSRAM_AWAKE - here I have only 0,8V according to repair wiki there should be 1,06V

I've also noticed that now board is taking 0,03A

any idea ? it is probably not good to inject voltage here ...

so it looks like according to repair wiki that this problem is connected to corrupted T2 (revive via another Mac OS not working as it just ends with padlock icon), restore the same.
or corrupted NAND (as I have on board only one NAND it's probably not only replacing NAND with another - or is it so simple ?

Or I can try to replace U7800 with another one ? does this make any sense ?

[mon2]

Re: MacBook Air A1932 820-01521 no boot 5v only

Yes, agree with the repair wiki details for 'No Power 20v, ~0.03-0.06a' case.

Wait on other comments as I do not have experience in this area of repair...yet.

[obelix24]

Re: MacBook Air A1932 820-01521 no boot 5v only

Anyone else any idea ?

[jma46]

Hi has repair wiki disappeared? I had it saved as a tab but nothing there?

[Admin]

Hi has repair wiki disappeared? I had it saved as a tab but nothing there?

Hi jma46, is this part of Badcaps forum or an external link? I've been tidying empty older groups so just a bit worried i've deleted something required. Can you clarify?

[mon2]

Noted the same a few days ago but it appears that the repairwiki website has been upgraded so the links have changed but content is still up there.

Found the following for the older content:

https://old.repair.wiki/w/Repair_Wiki