MacBook Pro A1989 liquid damage

[MrBojangles]

Hi!

First post here...

MacBook Pro A1989 (820-00850-A) with liquid damage showing 5V.

I clean the board with alcohol and I get 20V. Fans spin but no chime or image.

I then check the board with a thermal camera and see a component, Q7030, that is hot. I clean extra around this area and now I'm back to 5V.

So... that means it's time to learn how to use schematics and boardview and what I've learned so far is that PPBUS_G3H is the "always on" power mode.

I've checked multiple components pertaining to PPBUS_G3H and they are showing 5V which tells me that the problem is not there.

I need to check the "next level" of power and this is where I'm totally lost.

My questions is: Which components should I look at and what exactly am I looking for?

My guess is that I'm looking for a component which doesn't have the voltage it's supposed to have but I'm not clear on knowing what the voltage should be and how to identify the faulty component.

Sorry for the long post but as you can see I'm quite new to this

[mon2]

Hello. Welcome. The designs with USB Type C are power delivery (PD) designs. Respectively, the external power adapter must be PD compliant and ideally should be the original adapter sold by the vendor for this target machine. Not impossible to use good quality 3rd party adapters with suitable e-marked PD cables rated @ 100W or higher.

Once this setup is correct, there is a communication that will occur between the external power adapter (PD type) and a local PD controller ('ACE') onboard this logic board. Each power usually is fitted with its own PD controller. Each such controller has local firmware to offer the PD controller stack (software / firmware) to request the PD contracts (voltage & current) from the external power adapter. The 5 volt PD contract is a power up default. The PD adapter will share a list of supported contracts from which the ACE controller (CD3215 / 3217 / 3218, etc.) will select the best choice to power the machine. Usually it is the 20V contract.

You are at 5 volts only. Study the ACE controllers and confirm the LDO rails are present for the connector you are testing. The dual mosfet you are observing may be defective and/or the ISL9240 is defective. The ISL9240 is a buck / boost regulator. When 5 volts is used at the input, the ISL9240 should boost this voltage to a higher one (~12 volts - check the repairwiki to confirm). After all is well, the ISL9240 will further boost this boosted voltage to ~13 volts. That is, once the board is operational, 20V will be used as the input voltage and this ISL9240 will shift into buck regulator operation (ie. high voltage in / low voltage out rather than boost mode).

You do need the ISL9240 to be working for the 20V to be created. Review the document by piernov on how 20V is selected on such boards - it is important.

CD3215 Bootup Sequence - LogiWiki

[MrBojangles]

Hello. Welcome. The designs with USB Type C are power delivery (PD) designs. Respectively, the external power adapter must be PD compliant and ideally should be the original adapter sold by the vendor for this target machine. Not impossible to use good quality 3rd party adapters with suitable e-marked PD cables rated @ 100W or higher.

Once this setup is correct, there is a communication that will occur between the external power adapter (PD type) and a local PD controller ('ACE') onboard this logic board. Each power usually is fitted with its own PD controller. Each such controller has local firmware to offer the PD controller stack (software / firmware) to request the PD contracts (voltage & current) from the external power adapter. The 5 volt PD contract is a power up default. The PD adapter will share a list of supported contracts from which the ACE controller (CD3215 / 3217 / 3218, etc.) will select the best choice to power the machine. Usually it is the 20V contract.

You are at 5 volts only. Study the ACE controllers and confirm the LDO rails are present for the connector you are testing. The dual mosfet you are observing may be defective and/or the ISL9240 is defective. The ISL9240 is a buck / boost regulator. When 5 volts is used at the input, the ISL9240 should boost this voltage to a higher one (~12 volts - check the repairwiki to confirm). After all is well, the ISL9240 will further boost this boosted voltage to ~13 volts. That is, once the board is operational, 20V will be used as the input voltage and this ISL9240 will shift into buck regulator operation (ie. high voltage in / low voltage out rather than boost mode).

You do need the ISL9240 to be working for the 20V to be created. Review the document by piernov on how 20V is selected on such boards - it is important.

CD3215 Bootup Sequence - LogiWiki

Thank you for posting this. There's a lot of new stuff in here and I will have to research more in order to understand all the terms but I will that there is enough info here to help me.

[MrBojangles]

I did nothing but this time when I put the connector in I get 20.25 V and 0.5 A. One fan is spinning, the other is intermittently trying to spin. No chime, no display.

The following components are getting hot,

2R7
R47
U8160656 (Intel chip)
U810C656 (Intel chip)