A1534 820-00244 Macbook 0v at L9000

[bridges_4u]

I have got an 820-00244 logic board which consumes 14.71v and 0.311A when connected to an USB-C ampmeter. I have 0v at L9000, but at diode mode i get 0.298v. I also do not get voltages at L7430 & L7410. But I get 0.870v at L7230 & L7210. The logic was sent to another service center before reaching me. Is the CD3215 causing the voltage to stay at 14.71V???? All other voltages are present. Any clues.

Schematics Attached.

[bridges_4u]

Schematics

[mon2]

Flux and remove the fuse @ F3050. This will then isolate the power producer (adapter) and the power consumer (logic board) sides.

Power up again. What is the Vbus voltage now with the power adapter? Suggest to use the original OEM adapter or one that is rated for 100W with a certified 100W cable to power the unit. A good adapter & PD controller should negotiate 20V. Suspecting that you have a short issue on the main power rail.

The mosfets @ Q3100 should be investigated next.

What is the voltage to ground of PPBUS_G3H?

[bridges_4u]

Hi mon2,

Good to speak with you after a long while. Without F3050 removed, I have 8.65 at PPBUS_G3H. I think this comes with a 29W charger and the charger cable is not original, but of good quality though..!

[bridges_4u]

I will post the Vbus voltage after removing F3050 shortly.

[mon2]

Perhaps the power adapter does not offer 20V power delivery contracts? Test with another known good unit. The PPBUS_G3H is correct.

https://boards.rossmanngroup.com/thr...o-power.60238/

[bridges_4u]

mon2. I also had the same thought. but wanted to double check. The CPU on these boards go kaput due to no fan. Any further pointers?

[bridges_4u]

Unfortunately, I dont have another charger or same board.

[mon2]

I recall this unit being a bad design. You can check the CPU by removing all power and measuring the resistance to ground of the CPU vcore rails. If the resistance is too low, then the CPU is most likely dead. Since ppbus_g3h is ok, the CPU vcore high side should be ok but thermal fault is another case.

Test the voltage to ground of each inductor on the board. Testing for possible shorts.

This thread may help:

https://boards.rossmanngroup.com/thr...o-power.60238/

I have a power sequence chart for this model that can be posted if there is an interest.

[bridges_4u]

What about the USB-C ammeter reading? Should it be 20v or 14.71v? I was under the assumption that it should be 20V? Is there anything that could pull the voltage down from 20v to 14.71v? but in some posts at rossmanngroup, i saw that 14.71 is good.

https://boards.rossmanngroup.com/thr...ring-on.54444/
https://boards.rossmanngroup.com/thr...-no-ssd.58483/

[bridges_4u]

I recall this unit being a bad design. You can check the CPU by removing all power and measuring the resistance to ground of the CPU vcore rails. If the resistance is too low, then the CPU is most likely dead. Since ppbus_g3h is ok, the CPU vcore high side should be ok but thermal fault is another case.

Test the voltage to ground of each inductor on the board. Testing for possible shorts.

This thread may help:

https://boards.rossmanngroup.com/thr...o-power.60238/

I have a power sequence chart for this model that can be posted if there is an interest.

I would like to have that chart. I am indeed interested to go down the rabbit hole.

[mon2]

Note this comment:

14V could be correct, depending of charger model.

Power delivery is all about negotiations between the PD controller and the mated power adapter. The PD controller starts up with the power adapter as a power on default of 5v. Then the pd controller extracts the list of power delivery contracts (voltage & current). From this list of values, will select the highest / best suited pair to power the board.

Noting this, it is possible the power adapter is not capable of offering 20v, by design. Often, the pd contracts are published on the power adapter itself. We have seen units that do not offer 20v at all. For your power adapter, 15v may be max. While this may be ok, suggest to test with a unit able to support 20v pd contracts. They are very common these days.

Perhaps nothing is wrong with this machine other than the power adapter is not supporting 20v. Then proceed from there, if there is a fault. Ideally suggest 20v @ 5A = 100W rated power adapter. Such a unit is good to have in your toolbox. Always pair with a certified 100W rated cable since there is an e-marker chip inside of the cable end to announce to the pd adapter that it is ok and is safe to spit out 20V @ 5A since the conductors can handle this level of current. From personal experience, PD spec 1.0 did not have excellent controls over these negotiations and I almost burnt my hands in the lab.

[bridges_4u]

Good info mon2. I might need to order an adapter in for this. Do u think I should try reflowing the CPU on this before that. the 2.98v to the nand may be missing due to a contact problem under the CPU? If yes, what is the suggested temperature level for reflowing these kind of thin layered boards?

[bridges_4u]

When i did some research on the internet, some sources say that 30W charger is the one for A1534. But a few others suggest using a 61W charger. Is the 30W charger the right one for this model?

[mon2]

No, do not recommend the CPU reflow.

Wait, the power adapter may be ok (we use only 100W units at our service desk):

https://www.itpalacehub.pk/product/l...0a-29w-type-c/

Best to study the power sequence chart. Will post it here in a few.

[mon2]

Attached.

[mon2]

Another...

[bridges_4u]

Thank you for the reply mon2. These all make sense. Those voltages are already present. But the voltage to the NAND (2.98V)L9000 is absent, which comes from u9000 and the PCH. According to some posts at rossmanngroup, the SSD does not get detected. There is no short to ground on L9000, which leads me to assume that CPU may be the culprit. Cold or dry solder joints may be in play. Or else the CPU itself may be kaput? Plus there is not enough space to get the multimeter probes as well. Am i right?

[mon2]

Remove all power. Meter in resistance mode. Measure the resistance to ground of L9000.

Do you have the enable voltage @ PICCOLO_VEN1? PP5V_S5 available?

[bridges_4u]

Remove all power. Meter in resistance mode. Measure the resistance to ground of L9000.

Do you have the enable voltage @ PICCOLO_VEN1? PP5V_S5 available?

L9000 : Resistance to GND : 8.92kOhms
Yes. I do get PP5v5_S5 & PICCOLO_VEN1.

Regards