A1990 MBP 15" 2018 No Power

[Stephen]

Got a MacBook here with some odd readings.

5.12Volts constant on all 4 Ports
.43Amps constant on all 4 ports

This is a little different compared to other A1990 boards I have worked on. usually I can pinpoint the issue right off the bat but i am seeing some higher Amps than normal. I was assuming bad battery? Disconnected battery and yet still has the same amount of voltage and amps. Would love a little idea where to look before I pull the board out and look myself just to see if someone came across this before in these models.

Also no signs of water damage, board looks brand new.

Also it cannot go into DFU mode.

[mon2]

Re: A1990 MBP 15" 2018 No Power

The logic board is not dialing up the 20V power delivery contract from your external power adapter.

Start with the usual:

voltage of PPBUS_G3H ? If it is low, remove all power, meter in resistance mode -> check the resistance to ground of PPBUS_G3H (F7000, pin # 2).

Next, confirm the voltage of each LDO rail on each CD3215.

Each CD3215 must be functional to allow for the 20V contract to be selected.

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

[Stephen]

Re: A1990 MBP 15" 2018 No Power

This has a CD3217 which is a little different in the grand scheme of things. we are well aware of the CD3215 issue on most boards but since this is an 2018 they use a different Chip. But however I will go down the power rails this week.

[mon2]

Re: A1990 MBP 15" 2018 No Power

What is the logic board # for your unit ?

My 820-01814 (A1990) shows the ACE controllers as CD3215A onboard.

[Stephen]

Re: A1990 MBP 15" 2018 No Power

All T2 boards have CD3217 chips

[mon2]

Re: A1990 MBP 15" 2018 No Power

Ok but what is the 820-xxxx # ? Just trying to locate the proper schematic to reference.

[Stephen]

Re: A1990 MBP 15" 2018 No Power

820-01814-A schematic

Oh you are right, they are CD3215 chips on this model. WTH? Odd. Yeah I guess it may be a CD3215 issue most likely. I will trace back further this week

[Stephen]

Re: A1990 MBP 15" 2018 No Power

Update on board:

Tested all LDO lines on all 4 USB chips. All checked out good, after flipping the board the voltage jumped to 20V and stayed. I was confused, i disconnected the meter reconnected it and it stayed at 5V. Any idea why this happened? I am thinking it has something to do with u7000?

[Stephen]

Re: A1990 MBP 15" 2018 No Power

Also PPBUS_G3H is present.

[mon2]

Re: A1990 MBP 15" 2018 No Power

Different logic flow on the Type C connectors.

That is, if you flip the connector one way, one side of the blade is functional and vice versa for the other side.

Review the same connector you are using for the power adapter -> what is the voltage ?

Then unplug the adapter and flip the connector 180 degrees and test again.

This has to do with the CC1 and CC2 pins on the Type C connector.

Each is used for a single wire communication line to extract the power delivery contracts. CC1 is on one side; CC2 is on the other side.

PPBUS_G3H is present

Yes, U7000 will act like a BOOST circuit and boost the 5v0 input to the desired target PPBUS_G3H voltage.

Eventually when all is well, 20V power delivery contract will be selected and then U7000 will act like a BUCK circuit and then LOWER the 20V to the desired PPBUS_G3H voltage rail.

[Stephen]

Re: A1990 MBP 15" 2018 No Power

what I meant is I flipped the board not the USB C meter. it was connected still and it just moved to 20V for no reason at all then i disconnected reconnected it and it went back to 5V and not moving.

[mon2]

Re: A1990 MBP 15" 2018 No Power

Be very very very careful with Type C connectors & mating cables. The power delivery industry is only realizing this now and late to the party on how easy it is to kill the Type C controllers with cross shorts of the dainty contacts.

That is, 20V shorting across the CCx (5 volt tolerant contacts) is instant death unless there is protection for this condition. As noted, now we are seeing such parts on the market from ST / TI and others.

I recall working with PD 1.0 spec and almost scorched my hand working with 20V contracts. VIA was the PD chip inside the cable and they admitted that improvements could be made which they now state is protected against such high surges on the CCx lines.

I would recommend to remove all power, meter in diode mode -> check the readings for the CCx lines; D+ and D- lines for each CD3215 controller.

Also suggest to confirm the presence of the LDO rails on each CD3215 device.

Also confirm that the power adapter is still able to deliver 20V with a known good Type C load. I know that we killed a LVSUN (great adapter while it worked for us) 90W adapter for our work bench with a similar cross short event. Will order another from Asia.

[Stephen]

Re: A1990 MBP 15" 2018 No Power

I am so lost lol

20V came back for no reason. then unplugged it back at 5Volts. Here is the thing
when it goes to 20V the amps drops to .04 amps while when in 5VOLTS the amps are in .39-.42

[Stephen]

Re: A1990 MBP 15" 2018 No Power

All LDO rails are present and correct as well.

[mon2]

Re: A1990 MBP 15" 2018 No Power

Are you using an official Apple power adapter ? Is it able to support this laptop ?

How many watts rating for your adapter ?

This model has the dainty USB C paddle boards. With the power off, can confirm that the contacts (friction fit) are solid ?

What is the result if you select a different Type C connector to power this logic board ?

Test each and every Type C port on the unit. Recommend that you unplug the power adapter from the wall -> then mate the adapter Type C connector to your logic board -> then plug in the power adapter into the wall.

Do not want you to plug in the adapter while it is 'hot' which it is if plugged into the wall.

[Stephen]

Re: A1990 MBP 15" 2018 No Power

I believe after disconnecing the power and reconnecting one USB C port (chip CD3215) kept turning off and on on the USB C meter. I did this on all 4 ports and only one did this however if I moved the USB C meter around it stayed on without restarting. I believe this was the bad chip on the board most likely. I have to order CD3215 chips now and quite frankly I do not feel like reballing today LOL.

[mon2]

Re: A1990 MBP 15" 2018 No Power

What if, you remove the paddle board from the opposide side and apply onto the suspected bad port ?

Are the results improved ? Not a bad idea to source some replacement USB C paddle boards for the unit.

https://www.aliexpress.com/item/3296...rch-mainSearch

[Stephen]

Re: A1990 MBP 15" 2018 No Power

Thanks mon2 going to replace the USB C chips first then after the boards. I believe the boards are fine however I cannot fully confirm that until the chips are replaced. But it is odd it hits 20V when sitting for a second.

[Stephen]

Re: A1990 MBP 15" 2018 No Power

So there is no Voltage at PP1V1_UPC_XB_LDO_BMC It is missing on all 4 USB C chips. I replaced all the USB C Chips (CD3215) today and finally got a different voltage reading. 5.15Volts on all 4 ports and .28Amps on all 4 ports. It used to be 5.17Volts and .41Amps on all 4 ports. this time it dropped. And LDO is not present at the 1.1Volt Capictor

[Stephen]

Re: A1990 MBP 15" 2018 No Power

After reading may it be the U2890 Chip that is causing this loop to continue? Seems from what I read on piernovs post this was the case for a same situation in an A1707 I believe.