MSI B450M Mortar Max No power

[vcaina]

Hello Everyone!



Just wondering if I'm on the right path.

I have an MSI B450m Mortar Max MS-7b89 ver1.1 and it's not powering on. I started measuring around on some caps and mosfets and I found a dead short at one of the capacitors for the 3VSB circuit. The mosfets for CPU, and VRAM and other Mosfets doesn't read a short at all. First I tried to remove the capacitor but the short is still there. I checked the only related mosfet based on the BoardView file that I got and it's not shorted. But all the caps that are connected to the 3VSB net is shorted to ground at 0.9 ohms.

I was wondering if it is correct to inject voltage at the shorted cap that I found for at 3Volts to see where the shorted component is. I'm also not sure and I'm kinda new on this repair hobby.

Maybe some people had experience with a 3VSB dead short that can give insight to this issue.



Your response is greatly appreciated.



Thanks,

Vience

[stormanimal83]

Re: MSI B450M Mortar Max No power

wishing you the best bur for me it sounds like a bad chipset (PCH) the caps directly on the pch are shorted to ground also then...

[thebarber]

Re: MSI B450M Mortar Max No power

Hi, I am new to this hobby too, personnally I will inject voltage on this 3vsb, starting low 1 volt up to 3 max until I found the hot one, spray some alcool isopropilic to show were it desapear.

Good luck

[vcaina]

Re: MSI B450M Mortar Max No power

wishing you the best bur for me it sounds like a bad chipset (PCH) the caps directly on the pch are shorted to ground also then...

Hi Stormanimal83, thanks for the input. I measured around the caps around the chipset (FCH) and there were no direct short to ground. There is one cap but it connects directly to 3vcc based on the boardview file that I got. When I look at the 3VSB net, I don't see it directly connecting to the FCH. That's why I still have hope but who knows. I'll update once my short killer arrives.

[vcaina]

Re: MSI B450M Mortar Max No power

Hi, I am new to this hobby too, personnally I will inject voltage on this 3vsb, starting low 1 volt up to 3 max until I found the hot one, spray some alcool isopropilic to show were it desapear.

Good luck

Hi thebarber! Will it hurt the board if I go ham and directly inject 3v 5amps onto the 3VSB Circuit?

[stj]

Re: MSI B450M Mortar Max No power

maybe - if the short is on a thin trace you could burn the trace.
3v is o.k. but start at a lower current

[vcaina]

Re: MSI B450M Mortar Max No power

maybe - if the short is on a thin trace you could burn the trace.
3v is o.k. but start at a lower current

Thanks so much! I will update once the voltage injector arrives.

[vcaina]

Re: MSI B450M Mortar Max No power

Update on this Board Issue:

The Voltage Injector Module arrived. It's not techincally meant for this purpose but it does the job. It's a DC-DC Buck Module that does Constant Current. 1.2v-30V max 5amps.

I was able to isolate the problem component by injecting 3v 2a. I don't havea thermal cam so I smoldered my finger looking for hot place. Dump some alcohol and found it. Voltage injection is awesome! Anyway, based on the board view and schematics, I think it's a filtering capacitor for USB C Power? See pictures below:




I will now look for a replacement capacitor out of my dead a320m boards here and post an update once it works.

[vcaina]

Re: MSI B450M Mortar Max No power

Final update!

It's alive! Replaced the cap with from a donor board and the motherboard now powers up. It doesn't post though but that's a different issue from this. Thanks for the tips guys!

[JETFUAD]

Re: MSI B450M Mortar Max No power

Can you please give me the board view file of MSI mortar max (ms-7b89 v1.1)

[SMDFlea]

Re: MSI B450M Mortar Max No power

Can you please give me the board view file of MSI mortar max (ms-7b89 v1.1)

Desktop PC BIOS & Schematic Requests go here -> https://www.badcaps.net/forum/forumdisplay.php?f=15

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