help! macbook a2442 / 820-02098 does not turn on

[marcelofct]

Hello friends, I have this mac 820-02098 to which liquid spilled, I cleaned it and checking it is short-circuited, I do not have a green or orange light, PP3V8_AON is short-circuited, change capacitors and even so, it is still short-circuited, please help me to fix the macbook ,
these voltages I have

PPDCIN_AON : 5v
PPBUS_AON : 12.2v
PP3v8_AON_VDDMAIN :0v

[mon2]

Re: help! macbook a2442 / 820-02098 does not turn on

Remove all power.

Meter in resistance mode.

What is the exact resistance to ground of PP3v8_AON_VDDMAIN ?

[marcelofct]

Re: help! macbook a2442 / 820-02098 does not turn on

Remove all power.

Meter in resistance mode.

What is the exact resistance to ground of PP3v8_AON_VDDMAIN ?

PP3v8_AON_VDDMAIN 0.5 ohms
PP3v8_AON = 0.5ohms

[mon2]

Re: help! macbook a2442 / 820-02098 does not turn on

You have a short on this line. Check for any defective looking parts like capacitors.

Do you have an adjustable power supply that can support 1 volt output?

[marcelofct]

Re: help! macbook a2442 / 820-02098 does not turn on

You have a short on this line. Check for any defective looking parts like capacitors.

Do you have an adjustable power supply that can support 1 volt output?

yes, I have one, I tried to inject 1v but nothing is hot, it consumes 5 amps, what do you think it could be, I changed some capacitors and it's still the same, I look forward to your help

[mon2]

Re: help! macbook a2442 / 820-02098 does not turn on

Would you have a heatsink on the CPU? If yes, remove it to check if the CPU is heating up or not.

[marcelofct]

Re: help! macbook a2442 / 820-02098 does not turn on

Would you have a heatsink on the CPU? If yes, remove it to check if the CPU is heating up or not.

I inject 1v and nothing, cpu cold like a stone, I have looked at the motherboard and I can't find discolorations or broken capacitors, what do you recommend to continue doing?

[mon2]

Re: help! macbook a2442 / 820-02098 does not turn on

Consider to increase the current if possible on your power supply. If it is not possible, increase the voltage.

A key concern is if the high side CPU power rail is shorted with this one. This is the reason to keep the voltage as low as possible but increase the current.

Our short killer which claims to support peak current of 30A will often find offenders at 5-8A. Usually a bad ceramic and/or tantalum capacitor. They crumble under the current using 0v8 or 1v0 setting.

[marcelofct]

Re: help! macbook a2442 / 820-02098 does not turn on

Consider to increase the current if possible on your power supply. If it is not possible, increase the voltage.

A key concern is if the high side CPU power rail is shorted with this one. This is the reason to keep the voltage as low as possible but increase the current.

Our short killer which claims to support peak current of 30A will often find offenders at 5-8A. Usually a bad ceramic and/or tantalum capacitor. They crumble under the current using 0v8 or 1v0 setting.

I have a power supply up to 10a
from what I see the short circuit is not related to the cpu
I leave you an image of the sector

[mon2]

Re: help! macbook a2442 / 820-02098 does not turn on

Ok, crank up the current setting till someone cries uncle. You can apply IPA (alcohol) to see who is heating up. The heat will cause the IPA to mist or evaporate quickly.

[marcelofct]

Re: help! macbook a2442 / 820-02098 does not turn on

I got to 8.5a and didn't notice anything , do you think I should remove the capacitors that were with that leak and discard that sector?

[mon2]

Re: help! macbook a2442 / 820-02098 does not turn on

To confirm, the power supply is reporting that the rail is consuming 8.5A ?

At this setting, someone has to be heating up. Have you check both sides of the PCB?

[marcelofct]

Re: help! macbook a2442 / 820-02098 does not turn on

I'll continue tomorrow, it's time to go home. I'll let you know tomorrow, thanks for your help.

[marcelofct]

Re: help! macbook a2442 / 820-02098 does not turn on

I still can't find the shorted component, I've tried isopropyl alcohol and nothing, am I doing something wrong?
I inject voltage into a capacitor where the short is and nothing gets hot,