Completely dead MSI z490 tomahawk

[pavski]

Trying to troubleshoot MSI z490 tomahawk board and would appreciate your help. The board is completely dead and shows no activity when the power button is pressed.

I have tried to look at the Superio, the PSIN signal seems to be correct (goes from 3.3V to 0 on button press) but the voltage on PSOUT pin is quite low. I

t is only 0.8V which seems to be incorrect but goes to 0 when the button is pressed.

Can you please let me know if this is indeed incorrect and what else should I look at next?

Thanks!

[DynaxSC]

PSOUT seems to be strange value, normally should be 0 or around 3.3V.

But before analyzing the signals on the board, first you should rule out the BIOS image, if it's not demaged. Read out and backup the image with a hw programmer, and read it with eg. UEFITool, to see if the contents make any sense. You can compare it with a stock image.Then for test you can write a stock image to the BIOS SPI chip, and see if the board will start or not, this will give you final prove. Don't throw away the original image, as it contains speciific data for the board, eg. MAC LAN Address, UUID, S/N.

If BIOS is ok, then go to checking the PCH supply voltages (1.05V, 1.8V and 3.3V). They should be present in stand-by mode. If any isn't present, this means 99% the chipset is dead (shorted power supply line). Most easiest place to check this is on the inner pads of the caps which are soldered on the PCH around the silicon die.

If they are all present, next is to check whether the chipset asserts the SLP_S3# signal (can be found on pin 64 of SIO) after SuperIO asserted PWRBTN out (pin 60 or 61 of SIO, don't remember exactly). This signal from PCH usually starts the pre boot power sequence.

If SLP_S3# is not asserted, then it might mean that PCH is somehow demaged, despite the supply voltages are not shorted, or PCH get some wrong signals not allowing to assert SLP_S3, eg. some shorted signal on the board.


I could write and write more things to do, but just read many other posts on the forum, there is already a lot of similar cases, where you can get much more hints. Take the time for it, as it is not possible to write a full instruction how to diagnose a board, as there can be thousands of reasons why a board is not working.