820-00840 - Missing PPVCCGT_S0 - No display on internal nor external

[overshoot]

Hello,

I have that board that had a prior repair attempt.
I don't have any history from the customer on it.
The only thing that I saw was the board have been reflowed in the USB-C area. There was also 2 missing diodes of the keyboard I2C lines but I have put these back already.
Other than that, I can't find anything that looks funny or reworked.

I am getting 20V and the board seems to turn on.
I am getting all the expected voltages on the coils near the CPU but I am missing PVCCGT_S0 which is for the graphic cores if I am not mistaken.
I don't get a display on the internal display nor if an external display is connected.

Board turns on, gets 20V, seats around 0.5A and then goes back to 0A (which my known good board does not) then back to 0.5A and drops to 0.45A
I've measured the resistance to ground on PPVCCGT_S0 and I'm getting 2ohms, same with my known good board.

How to find out if I am getting the enable signal for that rail (PPVCCGT_S0)?
It's coming from the PMIC, correct?

That looks to me like a faulty CPU but I am wondering if I should give the PMIC a swap for the sake of trying (or a reflow first)?
Sounds like a good idea?

 

[overshoot]

CPU_VCCST_PWRGD is at 0.9V
ALL_SYS_PWRGD is at 3.3V
PM_PCH_SYS_PWROK is at 3.V
PM_RSMRST_L is at 3.3V
PM_PCH_PWROK is at 3.3V

 

[2informaticos]

As you have an working board, you should know iGPU voltage is not present when the board boots.
That voltage is not required, until high graphics load is detected; and we've already talked about that on the forum.

Post CPU core voltage after 10s; you should note a drop to 0.6V (if really boots).
Did you check for USB activity?
You can try known good BIOS dump.

BTW, some people reported intentionally damage done on boards by previous tehcnicians, when they cannot fixed them.
I recommend to inspect for ripped off components.

 

[overshoot]

I swear I've made a search first on that rail name to see if anything would show up so I could read that first but nothing.
I understand that you must be answering a lot of same things over and over again so I'm sorry about it.

I'll answer you shortly about that CPU vcore voltage, USB activity and once I've tried a known good Bios.

For the ripped off parts, like I said, I already did find those 2 diodes and when I saw that, I've spent almost 15mins looking around for other messed up parts but couldn't find anything else.

 

[overshoot]

So there is no USB activity, only power.
PPVCCCPU_S0G stays at 0.95V and never drops even after 30s.

I've tried a different Bios and same thing.

One thing to note is that the board goes to 19.5V and draws 0.5A for a few seconds and then amperage drops to 0 as if there was some kind of reset going on.
Then it goes back to 0.5A and will drop to 0.45A and 0.37A and stays there.

Known good board does not reset like that.

 

[2informaticos]

Pretty lost case.
Maybe faulty CPU, or damage induced by other service.