MSI MPG Z390 GAMING PRO CARBON MS-7B17 VER:1.1 - dead motherboard

Hello everyone,
Motherboard has no signs of life. I have flashed BIOS and problem is the same.
I am looking for someone's help/advice please.
In order to allow PSU to work motherboard has to ground PS-ON signal.
Unfortunately this is not happening here. 3.3V on power switch is present.
I have measured resistance to ground and none of the power lines has short (12V, 5V, 3.3V).
If all power circuits are not shorted to ground why PS-ON is not set/grounded by motherboard ?
What component is responsible for grounding PS-ON voltage and allowing PSU to supply voltages please ?
Thanking you in advance.
Regards,
Rafal S.

Hello Everyone,
I was not aware that I have missing voltage on Super I/O (start-up chip). There is no voltage on pin 1.
I have 3.3V on BIOS chip and 3.3V on power switch but the one to power Super I/O is not present.
Resistance on pin 1 is high so definitely there is no short. Which chip should produce power voltage for super I/O please ?
It looks like all comes back to PSU not being on and not providing all voltages.
I have measured Q60 (D-4.16V, S-4V, G-5V). For PSU to be working D is required to be grounded (0V).



What can be causing this problem ?
Thank you.
Regards,
Rafal S.

RafiManch писал(а):I was not aware that I have missing voltage on Super I/O (start-up chip). There is no voltage on pin 1.

Hello!
Note that the KBC (Super I/O) chip has a multiple power supply rails.
Voltage on pin 1 of KBC chip is "suspend" voltage, which appear when the machine is turned on (after pressing to the power button).
In Stand-By (when the machine is turned off) the KBC chip is powered by power rail "SIO_3VA" (pins 46, 85) and power rail "AVCC3" (pin 108).

Hello Matic,
Thank you for your clear explanation. Correct. I have 3.3V on all 3 pins of KBC.
I have 3.3V on power button and goes down to 0V when I press.
When I press power button KBC should allow PSU to switch on and provide all voltages.
Am I right ? Unfortunately this is not happening.
By tracing signal back to KBC pin 63 (PSON stays on 4V and is not going to 0V to allow PSU to work)



Thanks.

Measure the voltages to ground on pins 18, 26, 62, 64, 84, 99, 100, 101, 110, 116 of KBC chip.

Measure the voltages to ground on pins 60, 61 of KBC chip in the following cases:
a) Power button released.
b) Power button pressed.

Hello Matic,
Thank you for getting back to me.
Measure the voltages to ground on pins 18 (0V), 26 (0V), 62 (1.8V), 64 (0V), 84 (0V), 99 (3V), 100 (2.8V), 101 (3.3V), 110 (2V), 116 (1.5V) of KBC chip.
Measure the voltages to ground on pins 60, 61 of KBC chip in the following cases:
a) Power button released (both pins 3.3V)
b) Power button pressed (both pins 0V)

I have solved the problem.
1 resistor was missing from PCH area (other side of the motherboard).
I think it was knocked of when owner was installing or uninstalling motherboard.
This one is powering on and working now.
Thank you for your time trying to solve the problem Matic.