MSI Z390 MPG Gaming Plus wont start. No lights no Fans

[Vanillaboard]

MSI MPG Z390 Gaming Plus - 15.2V on GPU ATX Connector, Now Board Won't Start

Hello everyone,

I was experimenting with my MSI MPG Z390 Gaming Plus motherboard and accidentally applied 12.5V to the GPU ATX connector. The motherboard immediately powered off, and now it won't start anymore.
The graphics card seems to be fine, so no issues there.

I've measured the voltage at JFP1, and I'm getting 3.95V, as well as on the PS_OUT# pin of the SuperIO. As far as I know, these should be at 5V in standby, right?
Now my question is: where exactly do these 5V come from? I'm relatively new to this field, and from what I can find, the ATX 5VSB gets stepped down to around 1.5V as an input for standby.

Could anyone point me in the right direction here, or does it sound like the SuperIO might be faulty?
At the ATX24 connector, the ATX5VSB measures correctly at 5V.
I uploaded the shematics also:
https://www.badcaps.net/forum/troubl...-1-2-boardview

Thanks a lot for any help!

[DynaxSC]

You have most probably a short on the mobo. Check first all the stand-by voltages on the inductors, and look for shorts on them. For me it looks like you might have sent the chipset to heaven. On the chipset you will find very small caps, check with ohmmeter on the inner pads of these caps the resistances against GND, if you find some near 0 ohm, the chipset is fried. The 1.05V power line can have normally 25-60 ohms. The other power lines range of several hundred ohms to some few kohms.

BTW, did the CPU survive ? The GPU slot is driven directly by the CPU, some boards have however 4 driver chips between CPU and GPU slot, in this case these drivers may be fried.

[Vanillaboard]

You have most probably a short on the mobo. Check first all the stand-by voltages on the inductors, and look for shorts on them. For me it looks like you might have sent the chipset to heaven. On the chipset you will find very small caps, check with ohmmeter on the inner pads of these caps the resistances against GND, if you find some near 0 ohm, the chipset is fried. The 1.05V power line can have normally 25-60 ohms. The other power lines range of several hundred ohms to some few kohms.

BTW, did the CPU survive ? The GPU slot is driven directly by the CPU, some boards have however 4 driver chips between CPU and GPU slot, in this case these drivers may be fried.

Indeed, all the caps on the chipset show a short to ground. Unfortunately, I can't check whether the CPU is still intact, as I currently don't have a motherboard with the same socket available.
How can i check if the driveres are dead also?

Thanks for your answer!

[DynaxSC]

You can check the drivers with DMM reverse diode test, plus probe to mobo GND, minus probe to the driver output/input pin. You should get a reading of ca 0.3V +/- 0.1V, similar on all pins. You'll have to check 4 x 8 = 32 pins in total. You might also check the other side of the drivers towards CPU side. Another adittional check is measuring the +VCC resistance of the driver IC, but for this it has to be desoldered from board. If you would desolder the drivers heat the board from the bottom with hot air gun ca 450 C, 2cm distance (can take some time till the tin is liquid), heating from the top might demage the plastics body of the pcie slots, or you isolate them very good with at least 7-8 layers of capton tape and use also preheater from bottom 280-300C, 3-4 cm distance.

BTW, exchanging the chipset is really quite difficult, even more difficult than exchanging the LGA socket. Also a new chipset is the most expensive part on the mobo, so repairing such a failure might be on the edge of economical sense. Also a virgin chipset must be programmed after replacement with the Management Engine firmware, otherwise board may not function correctly (eg. M.2 ports will not work). And, this might not be all demages on the board, eg. SIO, VRM's also might be affected.

I don't want to say it's not worth the engagement, if you have good mechanical and soldering skills/tools it's all possible, but it will take time, and sometimes several attempts before success. But afterwards the success feeling is the best reward for the effort.

A tip: instead buying a new chipset on Aliexpress it might be better to buy another Z390 board, eg with demaged LGA socket, and transplant the chipset (must be reballed). Cost might be even the same. If you find an ASUS board, the chipset will have already some compatible Management Engine programmed. Other vendors might also work, but ASUS seems somtimes to tweak some things in the Management Engine, not using the original Intel version.