Dead Gigabyte GA-6VXE7+ with shorted +5vsb

[dafa_123]

Hello,

My Gigabyte GA-6VXE7+ just died. It will not power up at all with a good PSU. No apparent visual damage. When I check the power rails, I see that +5vsb is connected to ground. All the others are not shorted. The damage was most likely done when the old PSU died. I tested with a known good PSU and the MB won't even power or post. the only thing I can see is that +5vsb is grounded.

 

I've checked every component that I can check and none seem to be shorted. There are 2 capacitors and a regulator that have there pins to ground but I have removed them and tested them and they are good. The pads are still grounded even when the components marked in red are removed. Unless the issue is in the chipset, any idea where I can look?

 

 

Edited December 14, 2022 by dafa_123

[+Stephen Moss]

If you have a true short across one of the supply rails rather than just a low impedance so that it appear shorted then it is going to be a real pain in the ass to find.

 

The correct way to find a fault like that is to use a 5V power supply with a current limit set to say around 50mA or 100mA. The short should put the power supply into current limit mode dropping the voltage down to almost 0 limiting power to the PCB to prevent any further damage and protecting the power supply as opposed to essentially otherwise shorting the output of power supply without a current limit potentially damaging the test power supply.

Then you would need a circuit diagram and a current tracer to probe the current running along the respective PCB power track starting at the power connector, the current tracer should show a high current on the power rail up to the fault component, after the faulty component it will shown virtually no current as it is all going through the faulty component. Thus the faulty component can be identified.

 

But that is not an option for most people in which case you have the finger test (prod about until you get burnt) or purchase a can of freezer spray, liberally spray the entire PCB until it is all white and frosty should take about 10 seconds then apply the power. The faulty component should heat up a lot faster than the rest, even if it does not clearly point to a particular component it should clearly narrow down you search area. But again it would be best to use a power supply with a settable current so as not to risk damaging the test power supply.  

[dafa_123]

I tried to inject power on the +5vsb pin with the bench PSU and nothing is warming up. I cranked the amp up to 1 and only used around 200 mA at 5v. I think that I will mark this board as dead and use it for parts unless someone has another idea.

 

Thanks.

[dafa_123]

I removed the Gigabyte IC and the short is gone. If I find a working one I will replace it and hopefully the board will come back to life.

 

Thanks everyone.