MBA 820-01521-A Missing PP5V_G3S

[mon2]

Re: MBA 820-01521-A Missing PP5V_G3S

That is a low resistance.

Remove C4519 and check the resistance to ground again.

[Pedro147]

Re: MBA 820-01521-A Missing PP5V_G3S

with C4519 removed resistance to ground is still 62Ω.

All that's left on that line is U3900. That can't be good

RIP T2 :'(

[Pedro147]

Re: MBA 820-01521-A Missing PP5V_G3S

If that is indeed the end of the road, thanks for your help @mon2, I appreciate your time

[mon2]

Re: MBA 820-01521-A Missing PP5V_G3S

I believe that it is but wait on others to comment.

No sign of any liquid damage in this area or other parts of the logic board ?

Openly find it strange that a super low current rail has this resistance to ground - the schematics state a ~1 ma draw on this power rail.

I do not have enough experience in these newer models yet.

Now that we are starting to use our massive BGA rework station - will experiment soon with CPU and memory upgrades. The machine is fully automatic and can remove devices in under 5 mins.

[Pedro147]

Re: MBA 820-01521-A Missing PP5V_G3S

The guy I bought it from said that it had water damage on the audio board so he replaced that. That didn't fix the no booting so now I am trying to do that.

There is no evidence of corrosion on J6100 or anywhere else on the board. As we know all it takes sometimes is a loose end cap on a resistor to inhibit booting on any Macbook so I will keep looking. To me though, that low resistance on PP1V8_SLPS2R_SOC_LPOSC_RC can only be in the line from R4519 / C4519 connection to the T2 U3900 or actually in the T2 itself?

The BGA rework station sounds great so good luck with using that for some next level repairs

[mferna14]

Re: MBA 820-01521-A Missing PP5V_G3S

Just to add my input to all this... I had exactly the same problem & guess what, I had BRAND NEW CD3215C00Z DEFECTIVE... I removed these chips from a working logic board, re-balled both & all worked like charm. Please confirm CD3215C00Z, some Chinese sellers are selling defective ones. To be on the safe side purchase a def. logic board for parts in which these two chips are present.

[Pedro147]

Re: MBA 820-01521-A Missing PP5V_G3S

Just to add my input to all this... I had exactly the same problem & guess what, I had BRAND NEW CD3215C00Z DEFECTIVE... I removed these chips from a working logic board, re-balled both & all worked like charm. Please confirm CD3215C00Z, some Chinese sellers are selling defective ones. To be on the safe side purchase a def. logic board for parts in which these two chips are present.

That's great. Can I ask if you had 20 or 5v on charger and amp draw please? Thanks and yes I prfer pull rather than some Chinese cr*p. They are hit and miss at best

[mon2]

Re: MBA 820-01521-A Missing PP5V_G3S

If even a single cd3215 is defective, the voltage on the adapter will remain at 5 volts.

The cd3215 are power delivery controllers that extract the power contracts out of the adapter and then selects the best one to power the logic board.

Review the voltage of each LDO power rail on each cd3215 to confirm they are working.

https://logi.wiki/index.php/CD3215_Bootup_Sequence

[Pedro147]

Re: MBA 820-01521-A Missing PP5V_G3S

If even a single cd3215 is defective, the voltage on the adapter will remain at 5 volts.

The cd3215 are power delivery controllers that extract the power contracts out of the adapter and then selects the best one to power the logic board.

Review the voltage of each LDO power rail on each cd3215 to confirm they are working.

https://logi.wiki/index.php/CD3215_Bootup_Sequence

Hi @mon2. Not sure who your reply is meant for, but I am only asking about his specific circumstances in case I come across a similar case in the future thanks. Luckily I am pretty aware of the role that CD3215's play in requesting 20v from the charger. @mferna14's post was I believe just pointing out that Chinese CD's are notoriously unreliable rubbish at times and that you are better using ones from donor boards. Thanks anyway 🙏

[mferna14]

Re: MBA 820-01521-A Missing PP5V_G3S

That's great. Can I ask if you had 20 or 5v on charger and amp draw please? Thanks and yes I prfer pull rather than some Chinese cr*p. They are hit and miss at best

I had 5v 0.15amp on the amp meter display before I could replaced the CD3215C00Z. It was just my sixth sense that I was willing to do the extra work to make sure that I received a Defective CD' for China. I was not at all get the PP5V_G3S, missing 5v enable & Power Good was 1.5v only, but on the other side 3.3V all was good. Because upon tense observation under the MS, & checked nearly every caps' on the all rails I came to this conclusion that I might have received a def. CD'. & this was the case. You know the other thing I notice, replacing ONLY ONE (DEFECTIVE CD3215) will do the job, NOT Necessary to replace both. Now this is ONLY in my case & got a very positive result, the Logic board works like charm, all 4 side of the USB-C port connector works fine & charges battery well.