MacBook Pro 820 00923-A seems to boot but no activity

[Stevie_belfast]

Hi guys


Need a bit of help here if possible.



MacBook Pro 2017 A1706 820 00923-A



Came to me with no image and high fan spin.



Was taking 20V at 220ma, rebooting and back to 20V 220ma.



Found a short on PP3V3_TBT_X_S0 at C2976, little bit of water damage, fixed this and now it seems to go through the full boot order. High fan spin gone.


Takes 20V and goes to 700ma, 800ma, and finally settles at 500 - 600 ma. Seems normal to me. Though the fan does not start at all now.


Problem is, no image, no backlight, no external HDMI image either. No caps lock. No dong. Has trackpad click.


CPU gets warm.


USB Stick flashes twice, and a USB mouse lights up and stays lit up.


One other thing, 3 USB-C ports operate normally both orientations, though 1 port works one orientation, but draws nothing at all the other orientation.
CC2 for this port has a low resistance of 81 ohms.

CPU VCORE goes up to just over 1V, then settles around 0.8V to 0.9V.


This is where I'm now stuck.


Any help appreciated!


Oh and I know its Christmas Eve, but its been bugging me this one.


Happy Christmas all.

[mon2]

Re: MacBook Pro 820 00923-A seems to boot but no activity

What is the voltage to ground of PPBUS_G3H ?

[Stevie_belfast]

Re: MacBook Pro 820 00923-A seems to boot but no activity

Sorry, should have mentioned, all rails seem to be up.


Haven't got it to hand right now but in the kohms, PPBUS_G3H is 13.10V

5V S0 rails are there
3.3V S0 rails are there
RAM rail is there
NAND rail is there
ALL_SYS_PWRGD is up
SMC_LID is there when lid is opened

[mon2]

Re: MacBook Pro 820 00923-A seems to boot but no activity

Check the voltage to ground of PLT_RST_L.

Your case may be the same as here:

https://boards.rossmanngroup.com/thr...aindead.62519/

[Stevie_belfast]

Re: MacBook Pro 820 00923-A seems to boot but no activity

PLT_RST_L is there.

I'll have to try a good bios, but probably dead CPU then.


What a shame.

Well thanks for your help Mon2.

[cyber47]

Re: MacBook Pro 820 00923-A seems to boot but no activity

Hello,

i have currently the same problem ( my thread: https://www.badcaps.net/forum/showthread.php?t=113576 )

I think the difference between the case from the other forum and ours is, that we have usb activity.

Does your PPVCC_S0_CPU drops after a short time?

Does you have PPVCCEDRAM_S0_CPU? That is missing on my board because my CPU does not have CPU_ZVM_L

I have no solution yet but maybe this can give you a hint

[Stevie_belfast]

Re: MacBook Pro 820 00923-A seems to boot but no activity

Hello,

i have currently the same problem ( my thread: https://www.badcaps.net/forum/showthread.php?t=113576 )

I think the difference between the case from the other forum and ours is, that we have usb activity.

Does your PPVCC_S0_CPU drops after a short time?

Does you have PPVCCEDRAM_S0_CPU? That is missing on my board because my CPU does not have CPU_ZVM_L

I have no solution yet but maybe this can give you a hint

Hi Cyber47

Yes as mentioned above, it drops to around 0.8V - 0.9V after 10 seconds or so.

I will have to check those other rails you mentioned.

Hopefully the CPU isn't dead, I don't see how on mine as only PP3v3 was shorted and this was not shorted to cpu vcore.

[Stevie_belfast]

Re: MacBook Pro 820 00923-A seems to boot but no activity

Ok

I am also missing CPU_ZVM_L therefore I'm also missing PPVCCEDRAM_S0_CPU.

So same as you cyber47.

CPU_ZVM_L comes from the CPU, so does this confirm CPU is bad?

From questions asked in your thread cyber47, I checked these rails and they are all 0.9V

CPU_VIDSOUT, CPU_VIDALERT_L, CPU_VIDSCLK

[binoyroy]

Re: MacBook Pro 820 00923-A seems to boot but no activity

Ok

I am also missing CPU_ZVM_L therefore I'm also missing PPVCCEDRAM_S0_CPU.

So same as you cyber47.

CPU_ZVM_L comes from the CPU, so does this confirm CPU is bad?

From questions asked in your thread cyber47, I checked these rails and they are all 0.9V

CPU_VIDSOUT, CPU_VIDALERT_L, CPU_VIDSCLK

Check the LPC Reset and lpc fram and also lpc clock,thouse are responsible no display

[Stevie_belfast]

Re: MacBook Pro 820 00923-A seems to boot but no activity

Check the LPC Reset and lpc fram and also lpc clock,thouse are responsible no display

LPC reset, can't find it?

LPC_FRAME_R_L = 3.3V

LPC_CLK24M_SMC_R 1.6V

[cyber47]

Re: MacBook Pro 820 00923-A seems to boot but no activity

Ok

I am also missing CPU_ZVM_L therefore I'm also missing PPVCCEDRAM_S0_CPU.

So same as you cyber47.

CPU_ZVM_L comes from the CPU, so does this confirm CPU is bad?

From questions asked in your thread cyber47, I checked these rails and they are all 0.9V

CPU_VIDSOUT, CPU_VIDALERT_L, CPU_VIDSCLK

Hello Stevie_belfast,
sorry for the late reply!

I don't know if that confirm the CPU is bad, because it could be that the machine does not get into state S0, at least that is my understanding. I am not ready to give up yet, so i will look further into that

I also checked the rails and mine are also present with steady 1V.

Have you more information on your machine now?

Best regards