HP Probook 450 G7 DA0X8MMB6D0 Power-up problem

[badcapjerboard]

This is a spill that I got stuck on and am hoping for help.
I originally cleaned corrosion from the area between the cpu and back edge of the board. The charging light goes on white with 5-6 amber flashes then off when plugged in. No difference with battery only or together.
I had main power rail and 5v and 3v rails.
I noticed q402 in the spill area wasn't getting voltage and figured out r468 was missing with a damaged pad. I eventually managed to scratch out a trace next to that pad and solder a longer resistor and q402 had 3.3 input.
pu9200 is not outputting 1v. It has 19v in, 5v on pin 21, 3.3v en on pin 2, but no lx output and no pg on pin 1 I couldn't find a short or anything warm in the area. Under a camera u4000 got to around 30c and r575 and L400 area a bit warmer than the rest of the board, but i couldn't find a short in those areas or understand how they could be connected to the power up problem.

When i removed pl9201 nothing changed. I replaced pu9200 from a donor dead board where that chip was outputting 1v, but on this board same result.
+3V_DEEP_SUS is present and 1.8_deep_sus. present KBC_PWR_ON at r3309
The power button responds if held a long time and those pins on the ec seem to be active, but I didn't see any of these voltages affected by pressing the button
I tried flashing a different bios for both bios chips though not sure they were the right files to try. with the other files when plugged in the led didn't flash as long. I switched back to original files after.
A number of other low voltage chips are also not outputting(pu8700, pu8701,pu9602, pu9604 and other) and at least some seem to be because of CPU_C10_GATE# being 3.3v and VRPVDDQ_PG being 0v
I don't understand what makes CPU_C10_GATE# high and how to fix it or what is causing VRPVDDQ_PG to be 0v. How can i move foward?
Thanks

[badcapjerboard]

Interesting. I think SLP_S0# controls CPU_C10_GATE# so i measured r7703 which comes bj37 of the cpu, VRPPM_SLP_S0_N from when power plugged in it gave 1.5v a few seconds then briefly 0v then 3.3v and held..
I held down the power button and after 12 seconds it dropped to 0v and when i released the power button it went up to 1.5 then 0 then 3.3.

[mcplslg123]

Link schematic/bdv if available.Post clear pics of liquid spill area.

For 10 the gen onwards, you must have 1.8V/1.0V in standby condition. Since 1.0 is miising all the requisite for trigerring the mb is not present.

Very likely this has nothing to do with bios and still liquid spill area will give some clue.
Btw, liquid spilled under SOC?

[badcapjerboard]

Thanks for responding. I thought it was most likely from the spill area, but don't know how to progress at this point. After I found that resistor missing, I compared the whole area with photos someone else posted of the same board and couldn't find anything else obviously off.
Sorry SOC means cpu socket? I didn't see spill all the way to the cpu socket, though fairly close
I'm attaching the boardview i'm using and will post photos later.
The resistance of the coils in the area to ground are pl9201 15.6ohms, pl9001 14.1ohms, pl8903 3.3ohms, pl8902 3.3ohms, pl9000 5ohms

Link to boardview - https://www.badcaps.net/forum/troubl...probook-450-g7

[badcapjerboard]

These are the spill area with a usb microscope as i don't have lenses on the optical to show large areas. Some of those fets have water marks, but i'm not sure how to test them properly. @mcplslg123

[badcapjerboard]

Note: I checked the c-port which i hadn't done before and it is getting 5v and cycling, though usb-a ports get nothing

[mcplslg123]

The mb is only powered by usb-c port or is there a barrel type port also available?

If only usb-c, then it must negotiate to 20V for mb to turn on.

[badcapjerboard]

Yes i was using barrel the whole time for testing. I was just noting the usb-c outputs 5v. I tried input now on type c and it takes 19.8v .01a and board behaves the same as with barrel.

[badcapjerboard]

Does it make sense to take off the mosfets in the spill area to check them while the signals from pu8800 are not going to pu8900 etc, like VCORE_PWM1 and VCORE_CS1.?

[mcplslg123]

Liquid spill case is hard to solve online. Such faults can be diagnosed when you've the board on your table.
I still beleive something is wrong in the liquid spill area.
Btw, VCCSA present?

[badcapjerboard]

No, i only found 1.4v for VCCSA_SYNC1 nothing for the others

[badcapjerboard]

You were right👍 After poking around more i found pr9200 had one end eaten away. I replaced it with a donor and now pu9200 gives 1.0V_DEEP_SUS, but still no vcc. behaves the same
So 2 faults have been damaged/missing resistors in the spill area. I'll keep looking for more.

[badcapjerboard]

I am still missing +1.2VSUS, +2.5VSUS, and VCC

[badcapjerboard]

SLP_S4#_3R is active, i think that might mean it's cutting power to the 2.5vsus for ram, so maybe not supposed to be there in standy?

[badcapjerboard]

pu9201 now has +1.05V_DEEP_SUS and +3VPCU, but no VCCIO_EN and no VCCIO output

[mcplslg123]

1.2V/2.5V rail will come up only after switching on. So focus on why mb is not trigerring.

[badcapjerboard]

This new for me. Can vcc missing be the whole problem at this point, or do you think startup signals are not triggering from the ec?

[badcapjerboard]

I was trying with battery and plug. At one point after holding the power button for a while, when i let go the leds on the button board went on and stayed on. Still no picture.
In that state i checked and there was 1v VCCSA on pl9001, but still no vcc on pl9000, pl8902, pl8903. pl8701 was almost nothing, vcc_pe from the ec was still nothing.
I couldn't get this to repeat.

[mcplslg123]

You need to observe the motherboard under microscope very patiently. I still beleive something is rotten somewhere like rotten pads under resistor/caps and/or rotten tracks somewhere.

[badcapjerboard]

A lot of things look suspicious, but i'm not really finding anything. There is a test point that is destroyed right below that pr9200 i replaced, but everything connected on boardview seems ok it think.